This quasi-longitudinal descriptive case study evaluated problem behavior for an adolescent boy with developmental disabilities via repeated functional behavioral analysis (FBA) probes during a blinded cross-over from the atypical neuroleptic Risperdal (Risperidone) to Seroquel (Quetiapine). The repeated FBA probes showed no medication differences for the frequency or function of problem behavior. A second study was completed following a school placement change with repeated FBA probes and a stable medication regimen. In this context, problem behavior was negatively reinforced in the form of escape from task demands. School staff subsequently implemented a function-based treatment decreasing problem behavior during treatment sessions. Implications for collaboration between health care providers and behavioral specialists in the design of comprehensive interventions for problem behavior are discussed. (Contains 3 figures.)