Engagement behaviors are crucial for school success and are often targeted for improvement in school-based interventions. It may be helpful for both researchers and school-based practitioners to understand the likely impacts of interventions on engagement behaviors (e.g., to understand the extent to which engagement behaviors might change with treatment). For single-case studies designed to answer demonstration questions (i.e., including a baseline condition) and that were conducted in elementary classroom settings (N = 131), we calculated log response ratio and within-case standardized mean difference effect sizes for engagement dependent variables to establish benchmarks. We described differences based on study characteristics (functional relation determination, publication status, primacy of outcome), disability status of participants, and implementation characteristics (group size, implementer). Effect sizes (645 A-B comparisons) were heterogenous and varied based on functional relation determination, disability status, and implementation variables. More research is needed about additional variables that might explain heterogenous outcomes, especially for children with autism and behavioral disorders.