The effectiveness of behavior reduction strategies is likely affected by any number of ancillary variables. The purpose of this study was to provide a quantitative review of school-based behavior reduction interventions and some ancillary variables that may modulate the effectiveness of those interventions. Tau-U, an effect size statistic for single-case designs that takes into account level and trend, was calculated across studies, allowing for examination of several moderator variables including type of functional behavior assessment method used. Moderate intervention effects were found across all studies with a small yet insignificant difference between function- and nonfunction-based interventions. The largest difference in a moderator variable was intervention setting, with studies conducted in the natural environment producing larger effects than those in pull-out settings. Possible explanations for these findings, limitations of the study, and areas of future research are discussed.