In this Data Insight, the ADR Wales Housing & Homelessness research team explore experiences of ‘severe disadvantage’ among young people in Wales. These include homelessness, alcohol and drug misuse, and mental ill-health. Using linked administrative data, the team created a population-level cohort of young people. They then looked at the healthcare and other records of cohort members from their 16th birthday for a period of up to nine years. The analysis identified when young people were first recorded as experiencing each of the four severe disadvantages of interest. The findings help us understand how often severe disadvantages occur, how young people sometimes experience multiple different forms of disadvantage, and their timing as part of pathways to adulthood.