Compared to adults, interactions between youth and police more often lead to use of force and physical and emotional harm—harms that disproportionately burden the economically poor and Black youth who come into contact with police at relatively high rates. This talk brings together developmental science, historical sociology, anti-carceral perspectives, and primary research to make sense of “what works” (and doesn’t work) in implementing police reform for youth, sharing findings from an impact and implementation study of a law enforcement training program that seeks to improve police-youth interactions.