Youth clubs are community-based after-school programmes, typically offered free of charge to teenagers in underprivileged neighbourhoods. I provide the first causal estimates of their effects on education and crime, leveraging quasi-experimental variation from austerity-related cuts, which led to the closure of 30% of youth clubs in London between 2010 and 2019. I use difference-in-differences research designs and novel data to compare neighbourhoods affected by closures with those unaffected. Teenagers in areas affected performed nearly 4% worse in national high-school exams. Youths aged 10 to 17 became 14% more likely to commit crimes. Youth clubs provide key support in a lasting manner, particularly to teenagers from low-income backgrounds. The effects are due to youth clubs offering unique amenities that support positive behaviours rather than mere incapacitation. Closing youth clubs was not cost-effective; for every £1 saved from closures, there are associated losses of nearly £3 due to forgone returns to education and crime costs.