Research has addressed the consequences of being a victim of physical and relational aggression but less so the consequences of being an aggressor during adolescence. Consequently, relatively little is known about the extent to which aggression in early adolescence increases the risk of later aggression and other psychosocial problems. This study involves a representative sample of seventh- and ninth-grade students from Washington State (N = 1,942). Students were surveyed on recruitment and then again 1 and 2 years later to learn about ongoing behavior problems, substance use, depression, and self-harm behaviors. Surveys also included measures of several hypothesized promotive factors: attachment to family, school commitment, and academic achievement. Findings suggest that being physically and/or relationally aggressive in grades 7 to 9 increases the risk of aggression and possibly other problem behaviors after accounting for age, gender, race, and a prior measure of each outcome. Independent promotive effects were observed in most analyses, although family attachment appeared a less robust predictor overall. Implications for prevention include acting on the behavior itself and enhancing promotive influences to lessen the risk of agression and other related problems.