This study aimed to assess (a) the within- and between-person associations between daily stress and sleep; (b) the relation between childhood maltreatment and sleep; and (c) whether the relation between stress and sleep was moderated by the extent of childhood maltreatment among college students. Participants (N = 181) comprised the active control group in a previous intervention study. Participants completed a self-report measure of childhood maltreatment and 14 daily self-report measures of stressor exposure and severity (evenings) and 6 sleep measures (e.g., quality, duration; mornings). Experiencing more daily stressors than usual (within-person relation) was significantly associated with delayed sleep latency (i.e., time falling asleep). Greater daily stressor severity was also significantly associated with lower sleep efficiency within persons. Participants who reported more stressors in general had shorter sleep duration, poorer sleep quality, and less restful sleep (between-person relations). Students who reported more childhood maltreatment also reported significantly lower quality sleep and feeling less rested upon awakening. Childhood maltreatment did not moderate the within-person association between daily stress and sleep. Unexpectedly, at the between-person level, maltreatment moderated the association between stressors and stressor severity and several sleep parameters (e.g., efficiency and latency) such that there was a weaker relation between stress and sleep among those with more maltreatment. Interventions on campus could aim to reduce stress and improve sleep. Additional awareness of the prevalence of maltreatment and how it may be related to sleep also appears warranted. (PsycInfo Database Record (c) 2021 APA, all rights reserved).