In 1999, the UK Department for International Development (DfID) funded a major programme of research into young people's sexual and reproductive health in poorer country settings.Coordinated jointly by the Centre for Sexual Health Research at the University of Southampton, the Thomas Coram Research Unit at the Institute of Education, University of London and the Centre for Population Studies at the London School of Hygiene and Tropical Medicine, the principal objectives of the Safe Passages to Adulthood programme are to: - fill key knowledge gaps relating to the nature, magnitude and consequences of reproductive and sexual health problems amongst young people; - identify situation-specific key determinants of young people's sexual behaviour; - identify culturally-appropriate means by which barriers to good sexual and reproductive health can be overcome; - identify new opportunities to introduce and evaluate innovative programme interventions; - develop concepts and methods appropriate to the investigation of young people's sexual and reproductive health.The programme does not define young people through the use of age boundaries. Rather, it adopts a life course perspective in which the focus of interest is on individuals in the period prior to the transition to first sex, and up to the point of entry into marriage or a regular partnership.This spans the key transitional events of 'adolescence', and captures a period of high sexual health risk and distinctive service needs.Sexual and reproductive health includes physical and physiological processes and functions in addition to psychological and emotional aspects. It encompasses young people's capacity to decide if and when to have children; the ability to remain free from disease and unplanned pregnancies; freedom to express one's own sexual identity and feelings in the absence of repression, coercion and sexual violence; and the presence of mutuality and fulfilment in relationships.Beyond young people themselves, the Safe Passages to Adulthood programme focuses on policy makers and practitioners as 'gatekeepers' to the promotion of young people's sexual and reproductive health.