A native of Mexico City, Leal studied at the Escuela al Aire Libre, Coyoacan, under Alfredo Ramos Martínez, at age twenty; his fellows were Gabriel Fernández Ledesma, Rafael Vera de Córdoba, Ramón Alva de la Canal and Fermín Revueltas. He was one of the original muralists when that movement began in the twenties, his first mural, Los danzantes de Chalma, executed in encaustic. He taught painting at the Academia de San Carlos, and in 1927 was appointed director of the Centro Popular de Pintura in Nonoalco, whose mission was to make art accesible to the working classes. Leal was founder of the group ¡30-30!, which published a review in opposition to academic ideology in art. He collaborated with Diego Rivera, Jean Charlot, José Clemente Orozco, Ramón Alva de la Canal and David Alfaro Siqueiros in the Escuela Nacional Preparatoria's murals. He was one of the first artists to use indigenous themes as subjects for large scale murals. Leal painted several of them over next three decades such as the one for the Bolívar Amphiteathre in the Escuela Nacional Preparatoria in 1930-33, notable for its depiction of scenes from the life of Simón Bolívar. In 1952 was appointed Ministry of Culture and created a campaign for artists´rights in 1959. He left incomplete at his death a book on life at the San Carlos Academy.