AbstractThis study examined risk factors of physical aggression during transition from early to late adolescence using a two-wave longitudinal study. Specifically, we examined if risk factors in early adolescence predict physically aggressive behavior starting in late adolescence and why some adolescents desist physical aggressive behavior while others do not. The study sample consisted of 2289 Norwegian adolescents (1235 girls) who participated in the Young-HUNT1 study (mean age 14.5) and the follow-up study 4 years later, Young-HUNT2 study (mean age 18.4). One in six young adolescents reported engaging in physical fights. Moreover, physical aggression in early adolescence was significantly associated with male gender, attention problems, academic problems, being bullied, drinking alcohol, and smoking. Male gender and heavy drinking during early adolescence increased the risk for newly emerging aggressive behavior in late adolescence, whereas heavy drinking during early adolescence was a predictor for persistent versus desisting aggressive behavior in late adolescence.