Catlett was born in Washington, D.C. She graduated with a B.S. degree from Howard University in 1937, and received a master of fine arts (M.F.A.) degree in sculpture from the University of Iowa in 1940. At Howard University she became acquainted with African art and the work of Mexican muralists such as Diego Rivera. She studied with regionalist painter Grant Wood at the University of Iowa. Wood, who painted Midwestern scenes, told Catlett to paint what she knew best. For Catlett, this meant African Americans. After receiving her degree, Catlett taught at various high schools and colleges, serving for a time as head of the art department at Dillard University in New Orleans.
In the mid-1940s Catlett was awarded a Julius Rosenwald Foundation fellowship and used part of it to go to Mexico. In Mexico Catlett became involved with a printmaking workshop, Taller de Grafica Popular, which through its posters and illustrated books promoted literacy and other efforts to improve people’s