The purpose of this editorial is to introduce a new special section on single-subject designs that is designed to encourage the submission of papers to the Journal of Pediatric Psychology that utilizes single-subject methodology to investigate the efficacy of treatments for improving the health, mental health, and quality of life for children and adolescents. Methods and Results We review the case for using single subject designs in pediatric psychology research and provide examples from the literature of the three most commonly used designs: the reversal or withdrawal, multiple baseline, and changing criterion. We also describe limitations of single subject designs. Conclusions We hope this new special section will re-ignite enthusiasm among clinicians and researchers for using single subject designs to advance our field, provide pilot data for larger trials, and/or further document the efficacy of psychological and medical interventions with various populations