Non-cognitive skills are closely associated with adult socio-economic success. However, it is unclear whether interventions targeting those skills, rather than cognitive skills, can improve adult outcomes. It is also unclear whether interventions after early childhood can have lasting effects. We show that an intervention focused solely on non-cognitive skills at age 7 can change the lifetime trajectories for children with deficits of non-cognitive skills, increasing self-control and trust in adolescence, improving education achievement, and outcomes in early adulthood such as criminality, education, employment and social capital. We show that improvements in trust and self-control explain much of the impact on education and young adult outcomes, and argue that social skills are an important but neglected aspect of non-cognitive skill development. Using conservative assumptions in a simple framework, we estimate that, as a lower bound, $1 invested in this program yields about $14 in benefits over the lifetime of the participants.