Purpose/Objectives: To compare the sleep of children with acute lymphoblastic leukemia (ALL) during maintenance treatment with controls and to measure the effect on maternal sleep. Design: Comparative, descriptive. Setting: Pediatric oncology clinic and communities in Colorado. Sample: 26 dyads of mothers and children with ALL and matched controls. Methods: Mothers completed insomnia severity, mood, and stress questionnaires and wore a wrist actigraph, and mothers and children completed a seven-day sleep diary. Main Research Variables: Mother and child sleep parameters (e. g., total sleep time, sleep latency, sleep efficiency, awakenings); maternal insomnia severity, mood, and stress; child sleep habits. Findings: Mothers of children with ALL reported greater insomnia compared to controls, which was correlated with anxiety, depressive symptoms, and stress. Maternal groups did not differ on diary-and actigraph-measured sleep outcomes; both groups experienced sleep fragmentation. Children with ALL took longer to fall asleep and had more variable sleep patterns. Conclusions: Actigraph and sleep diary data indicated adequate maternal sleep duration and sleep latency. Self-reported insomnia severity in mothers of children with ALL suggested sleep fragmentation that may be undetected by these measures. Implications for Nursing: Oncology nurses are in a unique position to identify sleep problems in mothers and children with ALL, which may lead to recommendations for improved sleep and referrals for treatment.