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An independent K-12 school on a beautiful wooded campus, 3 miles from Washington, DC

About Our Trustees


Sameer Bhargava

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SAMEER BHARGAVA is Executive Vice President and Chief Financial Officer of Clark Construction Group, LLC, a building and civil contractor headquartered in Bethesda, MD, with over $4 billion in revenue. Previously, Mr. Bhargava was a Managing Director and Director of Corporate Development at The Carlyle Group in Washington, DC, focused on firm strategy and planning, firm acquisitions, fundraising initiatives, new product development and strategic relationships. At Carlyle, Mr. Bhargava also spent time in Carlyle’s U.S. Buyout Fund investment team, both in its Global Aerospace and Defense Group and its Global Industrial Group.

Mr. Bhargava has served as Chairman of the Board for Higher Achievement, an award-winning program serving more than 1,000 at risk middle school students in Washington, DC; Baltimore; Richmond; and Pittsburgh. Its proven model has demonstrated consistent increases in students’ GPAs, test scores and high school graduation rates. Mr. Bhargava also serves on the Board of Viagogo and the Dean’s Leadership Committee of the Harvard School of Design.

Prior to joining Carlyle, Mr. Bhargava was at Bain Capital, LLC, Advent International Corporation and McKinsey & Company.

Mr. Bhargava graduated from Harvard University with an honors degree in biology and received his MBA with distinction from Harvard Business School. He resides in McLean with his wife, Nimisha, and their four children.

Marjorie Brennan


MARJORIE P. BRENNAN is a physician specializing in pediatric anesthesiology at Children’s National Health System and is an assistant professor of anesthesiology and perioperative medicine at The George Washington University School of Medicine. She also holds a Master of Public Health. She is the medical director of Children’s Ambulatory Surgery Center in Montgomery County. Her areas of interest include muscle diseases of children, culture of safety, and global health.

Dr. Brennan has published book chapters in Essence of Anesthesia Practice and Progress in Anesthesia, A Manual of Practice Management for Ambulatory Surgery Centers, as well as articles in several peer-reviewed medical journals. She has been active in medical humanitarian work, volunteering for numerous trips to Vilnius University Children’s Hospital in Lithuania and Sacre Coeur Hospital in Haiti. She is a national speaker on issues of health equity in the developing world. She serves on the board of the Crudem Foundation, which operates a teaching hospital in Northern Haiti.

Dr. Brennan received her Bachelor of Science and her M.D. degree from the University of Michigan in Ann Arbor. She received her Master of Public Health at The George Washington University. She resides in McLean with her husband and three children.

Natalie Bush

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NATALIE F. BUSH earned both her Bachelor of Science in Nursing and her Master of Science in Nursing at West Virginia University School of Nursing. Upon graduation, she moved to Australia, where she established the first women’s counseling program in her region of the Northern Territory. The program provided free services to clients, with a focus on female health issues. Mrs. Bush also worked for the Manhattan Beach, CA, School District as a nurse. She has always been involved in school programs as she raised her three children. She served as a “Young at Art” docent for the Manhattan Beach School District and was a volunteer leader for the Chadwick School’s annual fund campaign, which raised $1.5 million annually with almost 100% participation. In addition, she served on the Chadwick School Board as a parent representative and, more recently, as a parent representative at The Potomac School.

Mrs. Bush is involved in nursing advisory board roles at several universities. She serves as the co-chair at Johns Hopkins University, chairs the West Virginia University Nursing Advisory Board, and is a member of the UC Davis Betty Irene Moore School of Nursing Advisory Board. She also serves on the Inova Foundation Board and is a member of their Nursing Council. In addition, Mrs. Bush volunteers at the Arlington Free Clinic and is a pet therapy volunteer at various DC-area facilities. She is married to Wes Bush, the chairman of the board, at Northrop Grumman Corporation. The Bushes reside in the Washington, DC, area.

Dax Cummings

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DAX CUMMINGS is a partner and managing director at The Kessler Group. He has significant experience in financial services with expertise in partnerships and endorsed program management and leads The Kessler Group’s efforts with key clients. Mr. Cummings joined Kessler in 2011 after spending the previous five years as a founder and COO of Revolution Money, a payments company that was acquired by American Express in 2010. Prior to founding Revolution Money, Mr. Cummings spent 14 years at MBNA serving as division president of the key U.S. Endorsed business, where he led the company’s 5,500 endorsing partnerships and a $65 billion endorsed consumer loan portfolio. In addition, he held executive positions leading MBNA’s regional offices, several business sectors, and the company’s new account activation efforts.

Mr. Cummings currently serves on the Advisory Board for the Connelly Center for Entrepreneurship at Washington and Lee University. He holds a Bachelor of Arts in politics from Washington and Lee and lives in McLean with his wife and two children.

Michael Davis

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MICHAEL L. DAVIS is head of U.S. institutional defined contribution plan specialists for T. Rowe Price. In this role, he leads the team responsible for expanding the firm’s reach and strategic engagement capabilities in the U.S. institutional DCIO segment. He is a member of the Americas leadership team and plays a key role in guiding the group’s U.S. DCIO strategy.

Mr. Davis has almost 25 years of industry experience. Prior to joining T. Rowe Price in 2016, Mr. Davis spent 17 years with JP Morgan, where he ultimately became head of the Western U.S. region for JP Morgan Asset Management and was later appointed deputy assistant secretary for the U.S. Department of Labor’s Employee Benefits Security Administration. He has also held senior positions with Prudential Financial and Calvert Investments. Mr. Davis has received a variety of civic awards and held several board positions. He earned a B.B.A. in finance from the University of Texas at Austin and an M.P.P. in public policy from the JFK School of Government at Harvard University.

Ellen Dwyer

ELLEN M. DWYER is a partner in the law firm of Crowell & Moring LLP, where she serves as Chair of the Firm’s Executive Committee and a member of its Management Board. Ellen represents employers in the full array of labor and employment matters, including litigation under federal and state anti-discrimination laws, trade secret and related fiduciary breach and wrongful discharge claims. She also conducts investigations and counsels employers across diverse industries on compliance issues ranging from sexual harassment to gender pay equity to whistleblower protections. 

Ellen serves on the Board and Executive Committee of the Leadership Council on Legal Diversity, an organization of law firm leaders committed to enhancing the diversity of the legal profession. Additionally, Ellen is a fellow of the American Bar Foundation.

Ellen earned her Bachelor of Arts degree from St. Lawrence University and her law degree from Cornell Law School. She resides in Arlington with her husband and three children.

Dan Fisher

DANIEL I. FISHER is a corporate partner in the New York and Washington offices of Akin Gump Strauss Hauer & Feld LLP, is the co-leader of Akin Gump's integrated special situations group and leads the transactional practice in the Washington office. Dan practices at the nexus of M&A, restructuring, securities and finance, and has market-leading experience in the unique issues raised by distressed and special situations. He primarily represents private equity and hedge funds in distressed transactions and restructurings and the portfolio companies of these funds in M&A, securities, and finance transactions.

A graduate of Columbia University and Vanderbilt University Law School, Dan previously clerked for Chief Justice Aharon Barak of the Supreme Court of Israel. He lives in McLean with his wife, Ashley, and their four children.

Jim Fleming


JAMES B. FLEMING is a partner at Columbia Capital, a venture capital firm based in Alexandria, VA, that focuses on communications, media, and information technology and manages approximately $3 billion in capital.

Mr. Fleming has served as a board member for numerous private companies and not-for-profit entities. He received his B.A. from Stanford University. He and his wife, Sheila, reside in Alexandria with their three children.


Stephanie Amann Kapsis


STEPHANIE AMANN KAPSIS '01 has dedicated her career to helping to strengthen public education and close the academic achievement gap. She currently serves as a senior advisor at KIPP DC, a growing network of open-enrollment college-preparatory public schools in Washington, DC, with a track record of preparing students in underserved communities for success in college and in life. Additionally, Mrs. Kapsis joined the Alexandria City School Board in January 2013 after receiving the greatest number of school board votes city-wide in the November 2012 election. In this role, she works to manage the superintendent, set the school system budget, and oversee policy for the school division.

Prior to these roles, Mrs. Kapsis worked as a dual language elementary school teacher in Brooklyn, NY, as a Teach for America corps member. She also served in multiple leadership roles on Teach for America’s DC Region administrative team.

Mrs. Kapsis graduated cum laude from Princeton University in 2005, receiving a bachelor’s degree in politics and certificates in Spanish and Latin American studies. While teaching, she received her Master of Science in teaching with a bilingual extension in Spanish language from Pace University.

A Potomac School “lifer,” Mrs. Kapsis grew up in McLean. She now lives with her husband, Jim, and their three children in the Del Ray neighborhood of Alexandria.

Bill Kilberg

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WILLIAM J. KILBERG is a retired senior partner with Gibson, Dunn & Crutcher. He has served on the firm’s executive committee and five-member management committee and as partner-in-charge of the Washington office. Mr. Kilberg is Chairman of the Board of Vorbeck Materials Corporation, a graphene-based electronics, communications, energy and composites company.

In 1973, Mr. Kilberg was appointed by President Richard Nixon as the solicitor (general counsel) for the U.S. Department of Labor, becoming the youngest person ever to be confirmed by the U.S. Senate for a sub-Cabinet post. He had served previously as associate solicitor of labor, general counsel of the Federal Mediation and Conciliation Service, and a White House fellow and special assistant to Secretary of Labor George P. Shultz. President Ronald Reagan appointed him to the Commission on White House Fellowships. Mr. Kilberg served as a co-chair of the National Finance Committees of both the John McCain and the Mitt Romney presidential campaigns and as chair of the Policy Committee on Labor for the Romney campaign. He is also a founder of the Palmer National Bank, now part of United Bank.

Mr. Kilberg is a charter fellow of both the College of Labor and Employment Lawyers and the American College of Employee Benefits Counsel; he served as president of the College of Labor and Employment Lawyers in 2014. He is a fellow of the American Bar Foundation, a member of the board of the American Friends of the Hebrew University (AFHU), president of AFHU’s Mid-Atlantic Region Board, and the legal advisory committee of the United States Holocaust Memorial Museum. He has served on the Virginia Israel Advisory Board as an appointee of former Virginia Governor McDonnell.

Mr. Kilberg graduated from Cornell University, which he attended on a scholarship from Local 3, International Brotherhood of Electrical Workers (IBEW), and received his law degree from Harvard Law School. He and his wife, Bobbie Greene Kilberg, are longtime Potomac parents and grandparents. All five of their children attended Potomac, and three of their eleven grandchildren are presently students. The Kilbergs have served on numerous Potomac capital campaign committees and co-chaired the last Parents of Alumni Campaign. Mrs. Kilberg previously served on the Board of Trustees.

Won Kim

Won Kim

WON KIM served 21 years at the Federal Communications Commission before retiring in 2016, working as a senior attorney in the spectrum and competition policy division of the Wireless Telecommunications Bureau. After her retirement, Ms. Kim has been devoting her time to her family, friends and the Potomac School.

Born and raised in Seoul, Korea, Ms. Kim is a graduate of Ewha Womans University, where she majored in English Literature. After earning a master’s degree from Ewha, she became a lecturer in the English Department and later won the British Council Fellowship to receive her second master’s degree in English literature from the University of Exeter, England. She continued her teaching at Ewha until she came to the United States in 1988 to start a family with her husband, Dr. Mu Hong.

As her second career path toward public policy and community service, Ms. Kim attended and graduated cum laude from Georgetown University Law Center in 1995. After law school, she has been actively involved in several community organizations and served on the boards of various non-for-profit organizations. At the Potomac School, her volunteer works include her service as head parent representative for the Lower School, a parent representative for the Upper School, and as a mentor to many new families. Ms. Kim and her husband live in McLean with their two daughters.

John Kowalik


JOHN KOWALIK became Potomac’s 14th head of school in 2013 after a decade as headmaster of The Peck School in Morristown, NJ.

Raised in the Boston area, Mr. Kowalik is a graduate of Archbishop Williams High School in Braintree, MA, and a member of that school's athletic and academic halls of fame. At Williams College, he majored in political science and captained teams in football and winter and spring track. He also has completed the Executive Management Program at Dartmouth’s Tuck Business School and earned a master’s degree in educational administration from Columbia University.

Mr. Kowalik spent 19 years at Delbarton School in Morristown, NJ, serving as a teacher and later dean of school and assistant headmaster. As head football coach for 16 years, he compiled a 138-29 record and won two state titles and nine conference championships. During his tenure at Peck, the school maintained a rigorous academic program distinguished by excellent teaching and developed a nationally recognized character program.

In 2009, Williams College profiled John Kowalik in one of its publications.

Mr. Kowalik and his wife, Carolyn, have four children: Jack and Liza are graduates of Notre Dame, Mark and Sara currently attend Notre Dame.

Tanya La Force

Tanya La Force

TANYA LA FORCE is an accomplished nonprofit and business leader with a track record of recruiting, leading and mentoring volunteers and employees to accomplish aggressive goals. She is a creative problem solver with more than 15 years of experience in the nonprofit sector. She currently is Chair and Founding Member of the Community Foundation for Northern Virginia’s Business Women’s Giving Circle, investing in innovative STEM and entrepreneurship programs for girls and young women. Prior to that, Ms. La Force was the Chairman of the Board and Founding Partner of the Children’s Science Center, building the first hands-on interactive science museum in Northern Virginia. Ms. La Force is a graduate of Leadership Fairfax and has strong ties in Northern Virginia. She cares deeply about the power of local nonprofit work and launched Mission Focused Consulting to help other organizations meet their potential. Prior to her nonprofit work, Ms. La Force was a CPA and Controller for industry leading companies. As a Potomac parent, she has volunteered on many committees, most recently serving on the Parent Association Executive Committee as the Intermediate School Head Parent Representative.

Ms. La Force is a graduate of Lafayette College with a BA in Economics and Business. She and her husband live in Northern Virginia with their three sons, all Potomac students.

Mary Lou Leipheimer


MARY LOUISE LEIPHEIMER served as head of school at Foxcroft School in Middleburg, VA, from 1989 until her retirement in 2014. A recognized leader in national independent school organizations, she has served on the boards of the Virginia Association of Independent Schools (VAIS), The Association of Boarding Schools (TABS), and the National Association of Principals of Schools for Girls (NAPSG). She currently serves as Vice-chair on the Westmoreland Foundation's Board of Directors, commonly known as Morven Park, and on the Board of Visitors for the Margaret Paxton Memorial Trust. In addition, she was a founding co-chair of the National Coalition of Girls’ Schools (NCGS). In 1999, Mrs. Leipheimer received the William B. Bretnall Award for Leadership from the Secondary School Admission Tests (SSAT) Board; in 2010, she received the Ruzicka Compass Premier Leadership Award from TABS.

Mrs. Leipheimer received her Bachelor of Science from Indiana University of Pennsylvania and was honored with the school’s Distinguished Alumni Award in 2009. A third generation teacher, she taught English and served as department chair, director of admission, director of development, and assistant head for external affairs during her Foxcroft tenure, which was interrupted only once, from 1978-1983 when she served as director of Emmanuel Preschool in Alexandria.

Mrs. Leipheimer has served on the Vestry of St. James Episcopal Church and the Margaret Paxton Memorial for Convalescent Children in Leesburg, and as chair of the Board of Directors of the Piedmont Child Care Center in Upperville, VA.

Rob McDowell


ROBERT M. MCDOWELL '78 is a partner with Cooley, LLP, providing strategic legal, business, and public policy counsel on matters in the telecommunications, media, and technology industries. He is also a senior fellow with the Hudson Institute, a non-partisan public policy research organization.

From 2006 through 2013, Mr. McDowell served as a commissioner of the Federal Communications Commission. He was appointed by presidents George W. Bush (2006) and Barack Obama (2009), and unanimously confirmed by the U.S. Senate each time. His second nomination made him the first Republican appointed to an independent agency by President Obama.

Prior to joining the FCC, Mr. McDowell worked in senior positions in the telecommunications industry. He served as senior vice president for the Competitive Telecommunications Association (CompTel), an association representing competitive facilities-based telecommunications service providers and their supplier partners. There, he had responsibilities involving advocacy efforts before Congress, the White House, and executive agencies. Prior to joining CompTel in February 1999, McDowell served as executive vice president and general counsel for America's Carriers Telecommunications Association (ACTA), which merged with CompTel at that time. He has served on the North American Numbering Council (NANC) and on the board of directors of North American Numbering Plan Billing and Collection, Inc. (NBANC).

Mr. McDowell's involvement in civic and political affairs spans four decades. He was appointed by Virginia Governor George Allen to the Governor's Advisory Board for a Safe and Drug-Free Virginia, and to the Virginia Board for Contractors, where he served for eight years. He is a veteran of several presidential campaigns; his work during the 1992 presidential campaign is cited in the Almanac of American Politics, 1994. Among many other endeavors, Mr. McDowell has twice been a candidate for the Virginia General Assembly. He is also on the Board of Visitors of Duke University's Sanford School of Public Policy and is a former chairman of the board of the McLean Project for the Arts, which strives to connect emerging artists with communities in the Washington region.

Mr. McDowell graduated cum laude from Duke University and the Marshall-Wythe School of Law at the College of William and Mary. After law school, he joined the Washington, DC, office of the national law firm of Arter & Hadden. He resides in Fairfax County with his wife, Jennifer, and their three children.

Robby Moser

Robby Moser

ROBERT D. MOSER, JR. is president and CEO of Clark Construction Group, LLC, headquartered in Bethesda, MD. In this position, Mr. Moser is responsible for setting the company's strategic priorities, as well as providing executive direction for the companies' national operations, which total nearly $5 billion per year. Throughout his more than 20-year tenure in the industry, Mr. Moser has led efforts to secure and build all manner of projects – from professional sports venues to transit infrastructure and national museums nationwide.

Mr. Moser earned his Bachelor of Science in civil engineering from the Virginia Polytechnic Institute and State University.

Lynne O'Brien


LYNNE F. O'BRIEN graduated from Princeton with an A.B. in political science and earned her law degree from Georgetown University Law Center. She worked as a Policy Analyst with the White House Cancer Moonshot office under Vice President Joe Biden. Previously, she worked as director of the Washington Government Affairs Office of DuPont Merck. She started her career in DC with Williams and Jensen, a lobbying/law firm in Washington, DC, focusing on healthcare clients.

Mrs. O'Brien is currently on the National Board of the Leukemia Lymphoma Society (LLS) and on the Board of Directors for the Prevent Cancer Foundation and the Cancer Support Community. Her volunteer work includes serving as Class of 1984 Annual Fund agent for Princeton University.

At The Potomac School, she is currently the Co-Chair of the Capital Campaign. She also has served as head parent representative for the Lower School, a fundraiser for the Annual Fund, and a room and team mother. Mrs. O'Brien and her husband, Gregory, live in McLean and have three children.

Norma Ramsey

NORMA C. RAMSEY is president of the W. Russell and Norma C. Ramsey Foundation.  Mrs. Ramsey is actively committed to philanthropic causes dedicated to at-risk families through education and health programs.  Along with her husband Russ, Mrs. Ramsey is a founding investor of Venture Philanthropy Partners which has invested over $100 million in Greater Washington’s most high performing non-profit institutions.

In addition to serving on the Dean’s Advisory Council of the Milken Institute School of Public Health at The George Washington University, Mrs. Ramsey serves on the Executive Committee of Children’s National Medical Center, the Foundation Board of Inova Health System, the Executive Committee of Knock out Abuse, the We Are Family Foundation and the Executive Committee of the University of Virginia Parents Council.  Mrs. Ramsey has also served as a member of the Executive Committee of the Wolf Trap Foundation for the Performing Arts as well as the Deacon Club Board at Wake Forest University.

An Emerita Trustee, Mrs. Ramsey served the Potomac School Board of Trustees from 2002-2011. During that time, she chaired the Building and Grounds Committee and personally oversaw the development of and initial implementation of the Master Plan.  Mrs. Ramsey currently serves as Chair of the Committee on Trustees and also serves on the Strategic Priorities Committee, the Building and Grounds Committee, the Development Committee, and Growing Ever Greater - The Campaign for The Potomac School.

Mrs. Ramsey earned a Bachelor of Arts from the University of Maryland and resides in Great Falls, VA along with her husband Russ, current student Paige ’24, and three alumni – Bailey ’10 (UPenn/GWU); Eric K-8 (WFU) and Mark ’14 (UVA).

Thomas Rietano

THOMAS J. RIETANO is a managing director in the Merrill Lynch Private Banking & Investment Group in Washington, DC, where his team oversees more than $2.5 billion in client assets. He has served on a number of not-for-profit boards in the greater Washington, DC, area.

Mr. Rietano is a graduate of the University of Vermont. He and his wife, Margaret, and their four children live in Washington, DC.

James Rooney

JAMES H. ROONEY is President of Avenir Corporation, a value oriented investment management firm located in Washington, DC that manages over $1 billon in separate accounts for individuals, families and institutions, including limited partnerships, foundations, pensions and endowments. Prior to joining Avenir in 1998, he worked in the energy business for Columbia Energy Group and Sonat, Inc., and held positions at Deloitte & Touche, LLP and J. & W. Seligman & Co., Inc.

Mr. Rooney has a BA in Economics and History from Duke University and an MBA from the Fuqua School of Business at Duke University. In addition, he is a CFA Charterholder and a member of the CFA Society of Washington. He has served on the boards of various charities and not-for-profits in Alexandria and northern Virginia.

As a Potomac parent, Mr. Rooney has been involved in the Fathers Association (FAPS). He and his wife, Jennifer, have three children, two of whom are Potomac graduates and one who is a current student.

Eric Rosenthal

ERIC W. ROSENTHAL ‘03 is a Director at Garrison Investment Group LP, a private equity firm based in New York, NY, focused on real estate, structured finance and corporate credit. The firm manages approximately $4.5 billion of discretionary capital on behalf of institutional limited partners. Mr. Rosenthal concentrates on debt and equity strategies across Garrison’s real estate mandate.

Mr. Rosenthal is a graduate of the University of Virginia. He served on Potomac’s Alumni Governing Council from 2011 to 2017, co-chairing its development committee for much of his tenure. He is a 2003 graduate of Potomac, as is his wife, Pamela Barris Rosenthal. They live in New York City with their two daughters.

Charles Rossotti

Charles Rossotti is currently an advisor to The Carlyle Group where he works on evaluating investments and advising  managements of portfolio companies, primarily in the fields of information technology and business services.

He serves on the boards of three Carlyle companies: Booz Allen and Hamilton;  Coalfire Systems; and Novetta Corporation. He previously served on the boards of  ECI Software; Quorum Management Solutions; Primatics Financial.   Compusearch Software, and the Wall Street Institute, all successfully exited from  2010 to 2016, and Apollo Global, partially exited in 2012.

In addition, he recently retired as non-executive chairman of the board of AES Corporation, a publicly owned global electric power company. He served on the board of Bank of America Corporation where he was chair of the audit committee until retiring in 2013 and on the board of Merrill Lynch before its merger with Bank of America.

On November 6, 2002,  Rossotti completed a five-year term as Commissioner of the Internal Revenue Service.  In 1970 Rossotti co-founded American Management Systems, an IT services and software company,  and until 1997 served at various times as President, CEO and Chairman.Prior to founding AMS, Rossotti served for four years in the Office of the Secretary of Defense, completing his service as Principal Deputy Assistant Secretary of Defense for Systems Analysis

In addition to his business activities, Mr. Rossotti serves on the boards of Capital Partners for Education and the  Comptroller General’s Advisory Committee of the Government Accountability Office (GAO)  In 2005, he served as a member of President Bush’s advisory panel on reform of the income tax.

Rossotti is the author of Many Unhappy Returns, a book about his experience turning around the IRS, published by Harvard Business School Press in March 2005. 


A.B. Economics, Magna cum Laude, Georgetown University, 1962

M.B.A with High Distinction, Harvard Business School, 1964

Susan Schieffer

SUSAN N. SCHIEFFER has nearly two decades of fundraising and development experience and has served on a number of non-profit boards. She holds a Master of Public Affairs from the LBJ School at The University of Texas and a Bachelor of Arts from Southern Methodist University.

Ms. Schieffer and her husband Steve Eichenauer have twins who are Potomac School graduates.



Karen Sonneborn

KAREN SONNEBORN is Co-founder and CEO of Honored (, a national nonprofit organization dedicated to recognizing, retaining, and inspiring great teachers and to elevating the profession of teaching.

Previously, she worked in business development at Warner Bros. in Los Angeles and investment banking at Goldman Sachs in New York.


Mrs. Sonneborn currently serves on the President’s Advisory Council, the Annual Giving Committee, and the Bridge Year Program Committee at Princeton University. She has served on the boards of San Francisco Ballet (Education Committee), East Palo Alto Tennis and Tutoring, Ambassadors for Lucile Packard Children’s Hospital, the Los Angeles Zoo, and KCET, Southern California’s largest public television station. While with KCET, she co-founded the award-winning KCET Council for Children and Families.

Mrs. Sonneborn graduated magna cum laude from Princeton University with a degree in economics and received an M.B.A. with honors from UCLA. She lives in Georgetown with her husband, Bill, and their three children.

Abigail Spangler

DR. ABIGAIL SPANGLER is president of the C.D. Spangler Foundation and serves on the Board of Directors of Spangler Companies, Inc. She is the founder of Protest Easy Guns, a national social movement to reduce gun violence in America, and founder of the Campaign to Close the Gun Show Loophole, which advocates background checks before gun sales. In these capacities, she works with gun violence victims' families and citizens across the nation.

Dr. Spangler holds a B.A. from Wellesley College and a Ph.D. in political science from Columbia University. Formerly a cellist with the Washington Metropolitan Philharmonic, she has two children, one a Potomac graduate and one currently attending Potomac School.

Mark Sullivan

MARK SULLIVAN ‘96 is an owner and operator of commercial real estate. His work experience includes various roles in the financial services industry. He is a Potomac School "lifer."

Martin W. Sumner

MARTIN W. SUMNER is a Managing Director of The Carlyle Group where he focuses on investment opportunities in the industrial and transportation sectors.

Since joining Carlyle in 2003, Mr. Sumner has led or been a key contributor to a number of the firm’s investments including Allison Transmission, Atotech, AxleTech International, Axalta Coating Systems, Centennial Resources Development, Nouryon, United Components, Veyance Technologies, and Wildhorse Resources, among others. Prior to joining Carlyle, he held positions with Thayer Capital Partners, a private equity firm and the strategy consulting group of Mercer Management Consulting.

Mr. Sumner received his M.B.A. from Stanford University, where he was an Arjay Miller Scholar and a B.S. in Economics, magna cum laude, from the Wharton School of the University of Pennsylvania.  He is currently a member of the Board of Directors of Atotech, AxleTech International and Nouryon and resides in Washington D.C. with his wife Meredith and three children.