We show that self control, time preferences, and values are malleable in adults, and that investments in these skills and preferences reduce crime and violence. We recruited criminally-engaged Liberian men and randomized half to eight weeks of group cognitive behavioral therapy, fostering self regulation, patience, and noncriminal values. We also randomized $200 grants. Cash alone and therapy alone dramatically reduced crime and violence, but effects dissipated within a year. When cash followed therapy, however, crime and violence decreased by as much as 50% for at least a year. We hypothesize that cash reinforced therapy’s lessons by prolonging practice and self-investment.