This study examined the feasibility and effectiveness of a comprehensive function-based intervention applied across multiple inclusive classroom settings. The participant was a middle school student diagnosed with Asperger Syndrome who exhibited chronic off-task behaviors across all academic environments. This study was conducted across two phases: (a) A descriptive functional behavior assessment (FBA) was conducted across all inclusive classroom environments and (b) a single, comprehensive function-based intervention was developed based on the results of the FBA followed by the implementation of a comprehensive function-based intervention in each inclusive classroom environment using a multiple probe design. The comprehensive function-based intervention markedly improved the participant's on-task behavior in each classroom setting. Furthermore, social validity ratings by each teacher revealed that the comprehensive, function-based intervention was preferable to the previously used classroom practices. Implications, limitations, and directions for future research are discussed.