The primary purpose of this quantitative synthesis of single-subject research was to investigate the relative effectiveness of function-based and non-function-based behavioral interventions for students diagnosed with attention-deficit/hyperactivity disorder. In addition, associations between various participant, assessment, and intervention characteristics were investigated. Eighty-two studies incorporating a total of 168 participants were included. Because no single effect size metric has garnered absolute support to date, three different effect size metrics were calculated: the standard mean difference, percent exceeding the median baseline phase, and improvement rate difference. Overall, function-based interventions were associated with significantly larger effects than non-function-based interventions. Interventions based on the functional analysis manipulations were also associated with larger effects. Limitations, directions for future research, and implications for practice are discussed.