Dellums worked in Washington, D.C., as a lobbyist for clients such as the East Bay Peralta Community College District and AC Transit, the public transit district charged with offering mass transit throughout the East Bay. Dellums's firm lobbied for Rolls Royce, a company that manufactures aircraft engines. He also worked on behalf of the San Francisco International Airport during its attempts to build additional runway capacity, which has been vigorously opposed by environmental groups. His company was engaged in community relations work for the Lawrence Berkeley National Laboratory which conducts scientific research on behalf of the Department of Energy, and has long had a contentious relationship with its residential neighbors and the Berkeley city council. In addition he lobbied for Bristol-Myers Squibb, a multinational pharmaceutical corporation.