Despite recent global declines in the rate of early childbearing, adolescent childbearing is a persistent challenge in many countries. Early motherhood is widely recognized as having negative consequences for the health of the young woman and her infant, as well as for their future economic, educational and social prospects.1–4 These risks are particularly important in regions such as Central America, where poverty levels are high and access to resources is low.5–7 Compared with older mothers, adolescent mothers are at an increased risk of pregnancy-related complications; maternal mortality among adolescents aged 15–19 is twice as high as that among older women.8–11 Each year, 2.5 million adolescents worldwide undergo unsafe abortions, which put them at additional risk of adverse outcomes.12–14 In addition to these physical health risks, adolescent mothers attain lower levels of education, have fewer economic opportunities and experience higher rates of poverty,2–4,15 and their children are at increased risk of neonatal mortality, preterm birth, low birth weight and developmental delays.16–21 Furthermore, the children of adolescent mothers are more likely to suffer neglect and malnutrition, often due to the poorer social and economic status of their mothers.22,23 Such children also face elevated risks of low educational attainment and of teenage parenthood.24–26 Adolescent fertility is high in Central America: The latest national health surveys from 2002–2007 indicate that fertility rates for 15–19-year-olds are 137 births per 1,000 women in Honduras, 119 in Nicaragua, 114 in Guatemala and 104 in El Salvador, while the Latin American average is 75 births per 1,000 women aged 15–19.27–31 Although these four countries have experienced modest declines in total fertility rates over the last two decades, the rate of childbearing among adolescents remains extremely high. The already low levels of socioeconomic status and health care accessibility among these populations are further exacerbated by early childbearing. According to a recent assessment of the UN Millennium Development Goals in Latin America, El Salvador, Guatemala, Honduras and Nicaragua are far from achieving their goals of reducing maternal and infant mortality.32 Maternal mortality ranges from 170 deaths per 1,000 women in El Salvador and Nicaragua to 280–290 deaths per 1,000 women in Honduras and Guatemala.31 These numbers have changed little in recent years, and evidence suggests that maternal mortality ratios are persistently higher among adolescents than among adult women.8 Infant mortality in Guatemala and Honduras also remains elevated in relation to Latin America overall, despite declines over the past decade (30 and 28 deaths, respectively, per 1,000 live births vs. 22 deaths per 1,000 live births).33 High infant mortality rates are associated with poverty and low educational attainment, factors for which adolescent mothers are at increased risk.34,35 Indeed, a UN report argues that “It will be impossible to attain the Millennium Development Goals related to maternal health unless resources are invested and effective action taken among the adolescent and youth population.”32 To address reproductive health issues among adolescents in Central America, the trends and causes of sexual and childbearing behaviors must be understood. To date, no study has specifically examined and compared long-term trends in adolescent sexual and reproductive behavior in El Salvador, Guatemala, Honduras and Nicaragua. This analysis uses data from multiple time points for each country over the past two decades to describe trends in sexual experience, union status, contraceptive use and childbearing among women aged 15–19. The analysis also assesses whether selected demographic and socioeconomic factors are associated with trends in sexual activity and childbearing in these countries.