This randomized controlled study examined disciplinary outcomes for 201 students who made threats of violence at school. The students attended 40 schools randomly assigned to use the Virginia Student Threat Assessment Guidelines or follow a business-as-usual disciplinary approach in a control group. Logistic regression analyses found, after controlling for student gender, race, school level, and threat severity, that the 100 students in the threat assessment group schools were more likely to receive counseling services (odds ratio [OR] = 3.98) and a parent conference (OR = 2.57), and less likely to receive a long-term suspension (OR = 0.35) or alternative school placement (OR = 0.13) than the 101 students in the control group schools. Implementation fidelity was associated with decreased long-term suspension (OR = 0.73). These results provide strong empirical support for the use of student threat assessment in primary and secondary schools. (Contains 3 tables.)