Previous studies have focused on whether a trial-based functional analysis (FA) yields the same outcomes as more traditional FAs, and whether interventions based on trial-based FAs can reduce socially maintained problem behavior. We included a full range of behavior functions and taught 3 teachers to conduct a trial-based FA with 3 boys with developmental and intellectual disabilities who engaged in problem behavior. Based on the results of the trial-based FAs, we developed and conducted 5 function-based interventions, using differential reinforcement of an alternative behavior and extinction in all but 1 case. In the remaining case, we used noncontingent reinforcement. All interventions led to reductions in problem behavior and increases in alternative behavior.