Challenging behavior can create significant obstacles to academic and social progress for individuals in a school setting, particularly those with developmental disabilities. Functional assessments such as rating scales, ABC analyses, and functional analyses, are evidenced to be the most effective methods for identifying the maintaining variables of problem behavior and for informing efficient, function-based interventions. Although the empirical literature and federal mandates support the use of functional assessment, obstacles to the practical application of these procedures in school settings (e.g., training requirements, time constraints) may deter school staff from using them consistently. Recent research has addressed some of these concerns, and there is developing evidence for briefer, more user-friendly versions of functional assessment. Practitioners can maximize the effectiveness of the intervention process by linking treatment components to functional assessment results. Effective, function-based interventions are comprised of procedures designed to reduce target behavior prior to it occurrence, procedures to teach the learner to access the reinforcer (or an adaptive alternative) appropriately, and systematic procedures for responding to the behavior. Future studies should continue to refine these procedures and address the use of functional assessment with ext ended populations, including adults with disabilities and typically developing children.