This chapter explores typical sexual development, as well as aspects of precocious, problematic and inappropriate sexual behaviours. It examines some of the common social and health risks arising from unprotected sex, including sexually transmitted infections and unplanned pregnancy. The chapter discusses constructive ways of supporting teenage parents. It considers cultural aspects of sexual violence against girls and women and the impact of legislation and community action in addressing this issue. The chapter looks at some interventions to heighten young people’s awareness of risks and to change attitudes in such areas as partner violence and in the domain of female genital mutilation/cutting. It shows sexual behaviours that are deemed to be harmful to the child/young person or to others in their social environment. Sexual health is a state of physical, emotional, mental and social well-being related to sexuality; it is not merely the absence of disease, dysfunction or infirmity.