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. (Contains 5 tables.)