Following the Mexican Revolution (1910–1920), the government made a major commitment to public education under its control. Centralization of education was via the federal Ministry of Education ("Secretaria de Educación Pública" or SEP). José Vasconcelos became its head in 1921 and proceeded to enact a wide range of educational programs, including indigenous education. The so-called "Indian problem," the lack of incorporation of Mexico's indigenous population into the nation as citizens, was an issue that the SEP tackled. Indigenous children were not to be taught in separate schools in their own languages but taught in Spanish along with non-indigenous, mestizo students. An early program was the formation of "Missionaries of Indigenous Culture and Public Education," which had the aim of imparting a secular worldview emphasizing "community development, modernization, and incorporation into the mestizo mainstream."