Education has been a high priority of the Castro government. In 1959 there were at least one million illiterates, and many more were only semiliterate. An extensive literacy campaign was inaugurated in 1961, when 100,000 teachers went out into the countryside. For the year 2000, UNESCO estimated the illiteracy rate of persons aged 15 years and over to be 3.6% (males, 3.5%; females, 3.6%). Education is free and compulsory for six years (6–11 years of age). In 1997, Cuba's 9,926 primary schools enrolled 1,094,868 students and employed 92,820 teachers. Student-to teacher ratio stood at 12 to 1. Secondary education lasts six years beyond the primary level. In 1997, 712,897 secondary students were instructed by 70,628 teachers. As of 1999, 99% of primary-school-age children were enrolled in school, while 80% of those eligible attended secondary school. The pupil-teacher ratio at the primary level was 12 to 1 in the same year. An innovation of the Castro government was the addition of agricultural and technical programs to the secondary-school curriculum; the work-study principle is now integral to Cuban secondary education. Students in urban secondary schools must spend at least seven weeks annually in rural labor. The first junior high schools, based on the work-study concept, were introduced in 1968. Catholic parochial schools were nationalized in 1961. As of 1999, public expenditure on education was 6.8% of GDP.
Cuba has five universities: the University of Havana (founded 1728), Oriente University at Santiago de Cuba (1947), the University of Las Villas at Santa Clara (1952), University of Camagüey (1974), and the University of Pinar Del-Rio. Workers' improvement courses (superación obrera), to raise adults to the sixth-grade level, and technical training schools (mínimo técnico), to develop unskilled workers' potentials and retrain other workers for new jobs, were instituted after 1961. Today, special worker-farmer schools prepare workers and peasants for enrollment at the universities and for skilled positions in industrial and agricultural enterprises. In 1997, tertiary education enrolled 111,587 students, with 22,574 teachers.