Sex education in schools is an adolescents' right, and can have health benefits, such as improved knowledge or increased condom use. In Asturias, a secondary school programme called Neither Ogres Nor Princesses educates pupils for four years with trained teaching staff and external workshops. This study examined whether this programme (a) improved adolescents' sexuality knowledge, attitudes and skills, and (b) increased condoms use. A quasi-experimental survey was conducted, with comparison arm, with a pre-test in the first year of secondary school (12- to 13-year-olds), and two post-tests: after the intervention (15- to 16-year-olds) and two years later (17- to 18-year-olds). A questionnaire with socio-demographic, knowledge, attitude, skill and sexual behaviour variables was used. The impact was evaluated with 'difference-indifferences' analyses. There was a greater increase of knowledge in the intervention arm in both post-tests, and an increase in skills in the first post-test. Girls in the intervention arm reported less practices with penetration and greater condom use the first time, this also among boys. However, the impact was limited in time. Interventions that aim to increase sex education in curricula with quality and fidelity are a priority to guarantee children's rights and their health.
Keywords: adolescents; behaviour change; evaluation; sexuality.