Medical treatment regimens for pediatric rheumatic diseases are complex, have delayed beneficial effects, and require consistent adherence over a long period of time. All of these factors place patients at risk for non-adherence that can compromise the benefits of treatment and the long-term health and quality of life for patients. This chapter provides a definition of adherence and reviews the prevalence of non-adherence to regimens for pediatric rheumatic diseases. It also describes various methods for assessing adherence, including assays, observation, electronic monitoring, pill counts, and provider or patient ratings of adherence. Studies which identify risk factors for non-adherence are also reviewed, with suggestions on how these risk factors might be addressed. The final section reviews the few studies that have reported on efforts to improve adherence to regimens for pediatric rheumatic diseases and offers strategies for providers to promote adherence with their patients.