Originally hired as an easel painter, in 1935 Alston became the first African-American supervisor to work for the WPA's Federal Art Project (FAP) in New York. This was his first mural. At this time he was awarded WPA Project Number 1262 – an opportunity to oversee a group of artists creating murals and to supervise their painting for the Harlem Hospital. It was the first government commission ever awarded to African-American artists, who included Beauford Delaney, Seabrook Powell and Vertis Hayes. He also had the chance to create and paint his own contribution to the collection: "Magic in Medicine" and "Modern Medicine". These paintings were part of a diptych completed in 1936 depicting the history of medicine in the African-American community and Beauford Delaney served as assistant. When creating the murals, Alston was inspired by the work of Aaron Douglas, who a year earlier had created the public art piece "Aspects of Negro Life" for the New York Public Library. He had researched traditional African culture, including traditional African medicine. "Magic in Medicine", which depicts African culture and holistic healing, is considered one of "America's first public scenes of Africa". All of the mural sketches submitted were accepted by the FAP; however, hospital superintendent Lawrence T. Dermody and commissioner of hospitals S.S. Goldwater rejected four proposals, due to what they said was an excessive amount of African-American representation in the works. The artists fought their response, writing letters to gain support. Four years later they succeeded in gaining the right to complete the murals. The sketches for "Magic in Medicine" and "Modern Medicine" were exhibited in the Museum of Modern Art's "New Horizons in American Art".