Parental depression is associated with offspring depression and sleep problems are prospectively associated with the development of depression. However, little work has examined sleep problems in the offspring of depressed parents and whether these problems partially account for the association between parent and offspring depression. This longitudinal study examined the indirect effect of sleep problems on the association between parent psychopathology and offspring depression in a sample of 10,953 10 to 12-year-old children participating in the Adolescent Brain and Cognitive Development (ABCD) study. Controlling for age, sex, and other forms of parent psychopathology, we found significant indirect effects of parent to offspring depression through parent and youth reports of youth insomnia and hypersomnia. We also found indirect effects of parent history of anxiety and drug use problems to offspring depression through insomnia, and indirect effects of parent history of anxiety, drug use problems, and alcohol use problems to offspring depression through hypersomnia. Our findings show that sleep may be a mechanism of the transmission of parent depression, anxiety, drug use problems, and alcohol use problems to offspring depression. Mitigating sleep problems represents a potential avenue for preventative interventions in youth with a heightened susceptibility to depression.