High rates of aggressive-disruptive behavior exhibited by children during their initial years of elementary school increase their risk for significant behavioral adjustment problems with teachers and peers. The purpose of the present study was to examine the unique and combined contributions of child vulnerabilities and school context to the development of aggressive-disruptive student behavior during first grade. Parent ratings and child interviews assessed three child characteristics associated with risk for the development of aggressive behavior problems in elementary school (aggressive-disruptive behaviors at home, attention problems, and social cognitions) in a sample of 755 first-grade children in four demographically diverse American communities. Two school characteristics associated with student aggressive-disruptive behavior problems (low-quality classroom context, school poverty levels) were also assessed. Linear and multilevel analyses showed that both child and school characteristics made independent and cumulative contributions to the development of student aggressive-disruptive behavior at school. Although rates of student aggressive-disruptive behavior varied by gender and race, the predictive model generalized across all groups of children in the study.