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. Seventy studies incorporating a total of 150 participants were included. Because no single effect size metric has garnered absolute support to date, three different effect size metrics were calculated: percentage of non-overlapping data, percent exceeding the median baseline phase, and the standard mean difference. Overall, function-based interventions were associated with significantly larger effects than nonfunction-based interventions. Interventions based on functional analysis manipulations were also associated with larger effects. Variables such as the intervention agent, the level of intervention restrictiveness, and the purpose of the intervention were also associated with larger treatment effects. Although each effect size metric measured differing aspects of treatment effectiveness, moderate to large correlations were found between metrics. Limitations, directions for future research, and implications for practice are discussed. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]