Objectives: To examine levels and patterns of HIV prevalence, knowledge, sexual behavior, and coverage of selected HIV services among adolescents aged 10–19 years and highlight data gaps and challenges. Methods: Data were reviewed from Joint United Nations Programme on HIV/AIDS HIV estimates, nationally representative household surveys, behavioral surveillance surveys, and published literature. Results: A number of gaps exist for adolescent-specific HIVrelated data; however, important implications for programming can be drawn. Eighty-two percent of the estimated 2.1 million adolescents aged 10–19 years living with HIV in 2012 were in sub-Saharan Africa, and the majority of these (58%) were females. Comprehensive accurate knowledge about HIV, condom use, HIV testing, and antiretroviral treatment coverage remain low in most countries. Early sexual debut (sex before 15 years of age) is more common among adolescent girls than boys in low- and middle-income countries, consistent with early marriage and early childbirth in these countries. In low and concentrated epidemic countries, HIV prevalence is highest among key populations. Conclusions: Although the available HIV-related data on adolescents are limited, increased HIV vulnerability in the second decade of life is evident in the data. Improving data gathering, analysis, and reporting systems specific to adolescents is essential to monitoring progress and improving health outcomes for adolescents. More systematic and better quality disaggregated data are needed to understand differences by sex, age, geography, and socioeconomic factors and to address equity and human rights obligations, especially for key populations.