After Yale he returned to Missouri and worked for State Attorney General, John Danforth. in 1977 Danforth was elected to the U.S. Senate. Thomas became a corporate lawyer for the Monsanto Company. Two years later he became Danforth's legislative aide in Washington, D.C.. President Ronald Reagan offered Thomas a job as the assistant secretary for civil rights in the U.S. Department of Education. He then became the chairman of the U.S. Equal Employment Opportunity Commission. Thomas was appointed to the United States Court of Appeals for the District of Columbia Circuit in 1990 by President George H. W. Bush. In 1991, Thurgood Marshall retired from the Supreme Court. Bush nominated Thomas to replace him.