This good practice guide introduces practitioners, policy-makers and researchers to two distinct but related concepts - risk and vulnerability. The guide explores how gender, race, culture, sexuality and social status all influence young people's experiences of sexual relationships and makes some more vulnerable to poor sexual health. Using case studies from Africa, Asia, Latin America and Europe, this resource sets out guidelines to inform work with especially vulnerable young people (including young people who sell sex, young people who inject drugs, and young migrants and refugees)