Low empathy has been implicated in antisocial, aggressive, and criminal behavior, especially among adolescents. Less understood is the extent to which empathy is amenable to treatment, and whether an improvement in empathy can mitigate the deleterious effects of known risk factors, such as childhood maltreatment. A sample of 11,000 serious juvenile offenders in long-term residential placement is leveraged to examine whether over cumulative traumatic exposure, measured by the adverse childhood experience (ACE) score, is associated with the initial level of empathy at admission to a residential program, and whether changes in empathy during treatment moderate the impact of ACEs on juvenile recidivism. Results show youth with higher ACE scores have less empathy at admission and both ACEs and empathy predict recidivism. Most importantly, large gains in empathy are able to dampen the effect of ACEs on recidivism.