Children and adolescents with acute lymphoblastic leukemia (ALL) receive treatment that relies on daily self- or parent/caregiver-administered oral chemotherapy for approximately 2 years. Despite the fact that pediatric ALL is uniformly fatal without adequate treatment, nonadherence to oral chemotherapy has been observed in up to one third of patients. Little is known about the reasons for nonadherence in these patients. This study used Straussian grounded theory methodology to develop and validate a model to explain the process of adherence to oral chemotherapy in children and adolescents with ALL. Thirty-eight semistructured interviews (with 17 patients and 21 parents/caregivers) and 4 focused group discussions were conducted. Three stages were identified in the process of adherence: (a) Recognizing the Threat, (b) Taking Control, and (c) Managing for the Duration. Doing Our Part was identified as the core theme explaining the process of adherence and involves the parent (or patient) taking responsibility for assuring that medications are taken as prescribed. Understanding the association between taking oral chemotherapy and control/cure of leukemia (Making the Connection) appeared to mediate adherence behaviors. © 2011 by Association of Pediatric Hematology/Oncology Nurses.