Poor adherence to pediatric cancer treatment protocols may prevent children and adolescents from realizing the potential benefits of therapy. This paper presents the evidence for a standard of care for supporting medication adherence. Databases were reviewed for articles examining adherence and including children and/or adolescents with cancer. Fourteen articles (i.e., qualitative, quantitative, review, and randomized clinical trials) were evaluated for rigor. There is moderate-quality evidence to support a strong recommendation for adherence to be assessed routinely and monitored throughout the treatment. Integrating the proposed clinical procedures into standard clinical care may improve outcomes for children and adolescents with cancer.