CONTEXT: Compared with the Latin American average, adolescent fertility is high in El Salvador, Guatemala, Honduras and Nicaragua, countries that also have high poverty levels and poor access to reproductive health care. METHODS: For each country, data were drawn from four national health surveys conducted between 1987 and 2007, and analysis focused on trends in sexual and reproductive behavior among adolescent females aged 15–19. Event history analysis examined transitions to first sexual intercourse, first union and first live birth across survey years; Cox hazard and logistic regression analyses assessed associations between selected demographic characteristics and these outcomes, as well as ever-use of a modern contraceptive method. RESULTS: The likelihood that adolescent females have initiated sexual intercourse has increased over time in El Salvador, Honduras and Nicaragua, and has remained stable in Guatemala. Meanwhile, the odds of having entered their first union have declined in Nicaragua and risen in El Salvador, but have not changed in Honduras or Guatemala. Notably, the likelihood that adolescents have ever used a modern contraceptive method has increased in all four countries over the survey years. Nicaraguan adolescents became significantly less likely to have had their first live birth over the study period. Finally, urban residence, education level and socioeconomic status were important predictors of adolescents’ sexual and reproductive outcomes. CONCLUSIONS: Programmatic and policy initiatives should focus on improving adolescents’ education and socioeconomic prospects, and efforts are especially needed to help adolescents delay the age at which they become sexually active and enter their first union.