Within 3-tier behavioral models, universal interventions are expected to prevent the onset of problem behavior in a majority of children altogether and to sustain improvements in child outcomes by the selected and indicated interventions. A cohort longitudinal design was used to assess the extent to which a 3-tier model achieves these expected outcomes. The respective universal, selected, and indicated interventions included Behavior and Academic Support and Enhancement, First Step to Success, and MultiSystemic Therapy. A total of 407 children in Grades K-3 from 1 of 4 longitudinal cohorts participated. The results of 2-level linear growth analyses indicate that the 3-tier behavior model achieved the anticipated outcomes with respect to social behavior. The results, limitations, and implications are discussed. (Contains 2 figures and 6 tables.)