The objective of the Cancer Control and Supportive Care (CCL) Committee in the Children's Oncology Group (COG) is to reduce the overall morbidity and mortality of therapy-related toxicities in children, adolescents, and young adults with cancer. We have targeted five major domains that cause clinically important toxicity: (i) infections and inflammation; (ii) malnutrition and metabolic dysfunction; (iii) chemotherapy-induced nausea and vomiting; (iv) neuro- and oto-toxicty; and (v) patient-reported outcomes and health-related quality of life. Subcommittees for each domain prioritize randomized controlled trials and biology aims to determine which strategies best mitigate the toxicities. The findings of these trials are impactful, informing clinical practice guidelines (CPGs) and directly leading to changes in the standard of care for oncology practice. With the development of new therapies, there will be new toxicities, and the COG CCL Committee is dedicated to developing interventions to minimize acute and delayed toxicities, lessen morbidity and mortality, and improve quality of life in pediatric and young adult patients with cancer.