Although both risk and protective factors are important components of etiological theories for antisocial behavior, far less is known about protective factors and their impact. This review summarized primary studies on the impact of different protective factors for antisocial behavior in youth. In total, 305 studies reporting on 1850 potentially protective factors were included. Each extracted factor was first classified into one of 77 mutually exclusive groups of similar factors (referred to as domains), after which a three-level meta-analysis was conducted to determine the protective effect of each domain. A significant and negative effect was found for 50 domains, which were therefore designated as being truly protective. The largest impact (r < −0.20) was found for higher levels of conservativeness, self-transcendence, life satisfaction, involvement in romantic relationships, the capacity to reflect or mentalize, peer relationships quality, prosocial peers, prosocial values, agreeableness, school self-esteem, parental control, general resilience, and social skills. Analyses revealed that the impact of some of the 77 domains was moderated by the youth’s age (five domains) and gender (four domains) as well as the severity of antisocial behavior they exhibit (two domains), indicating that the impact of these domains differs across subgroups of antisocial youth. Given the substantial number of factors that were identified as being protective for antisocial behavior in youth, this study discusses implications for future directions, assessment strategies, and (preventive) interventions.