He volunteered for the Peace Corps for three years, working in the Dominican Republic to support teacher training projects.

Williams announced August 21, 2012 that he was leaving his post after three years, citing personal and family considerations in his letter of resignation to President Barack Obama.

[4] In 1978 Williams joined the U.S. Agency for International Development (US AID), where he worked for 22 years, as a foreign service officer.

[4] Then he was promoted to senior management positions, serving as the Mission Director for the Eastern Caribbean Region based in Barbados, Deputy Assistant Administrator for Latin America and the Caribbean (LAC), Assistant Administrator for LAC, and as the head of the Executive Secretariat for USAID.

[4] In 2000, Williams left USAID to become Executive Vice President at the International Youth Foundation (IYF), a transnational nonprofit that focuses on leveraging corporate donations to assist young people in the developing world.

In July 2009, President Barack Obama nominated Williams, a career international development specialist, to serve as the new director of the Peace Corps.

[7] Williams testified to a congressional panel that the Peace Corps had not done enough to protect its volunteers and he would make it a priority to change that.

[8] Williams worked with Congress to institute reforms, such as heightened security, training and support for victims.