To examine the effect of school suspensions and arrests (i.e., being taken into police custody) on subsequent adolescent antisocial behavior such as violence and crime, after controlling for established risk and protective factors in Victoria, Australia and Washington State, United States (U.S.).This article reports on analyses of two points of data collected 1 year apart within a cross-national longitudinal study of the development of antisocial behavior, substance use, and related behaviors in approximately 4000 students aged 12 to 16 years in Victoria, Australia and Washington State, U.S. Students completed a modified version of the Communities That Care self-report survey of behavior, as well as risk and protective factors across five domains (individual, family, peer, school, and community). Multivariate logistic regression analyses investigate the effect of school suspensions and arrests on subsequent antisocial behavior, holding constant individual, family, peer, school, and community level influences such as being female, student belief in the moral order, emotional control, and attachment to mother.At the first assessment, school suspensions and arrests were more commonly reported in Washington, and school suspensions significantly increased the likelihood of antisocial behavior 12 months later, after holding constant established risk and protective factors (adjusted odds ratio [OR] 1.5, 95% confidence interval [CI] 1.1-2.1, p < .05). Predictors of antisocial behavior spanned risk and protective factors across five individual and ecological areas of risk. Risk factors in this study were pre-existing antisocial behavior (OR 3.6, CI 2.7-4.7, p < .001), association with antisocial peers (OR 1.8, CI 1.4-2.4, p < .001), academic failure (OR 1.3, CI 1.1-1.5, p < .01), and perceived availability of drugs in the community (OR 1.3, CI 1.1-1.5, p < .001). Protective factors included being female (OR 0.7, CI 0.5-0.9, p < .01), student belief in the moral order (OR 0.8, CI 0.6-1.0, p < .05), student emotional control (OR 0.7, CI 0.6-0.8, p < .001), and attachment to mother (OR 0.8, CI 0.7-1.0, p < .05).School suspensions may increase the likelihood of future behavior. Further research is required to both replicate this finding and establish the mechanisms by which school suspensions exert their effects.