This research sought to determine whether inadequate sleep conditions in childhood and sleep problems in young adulthood in part explain the relationship between childhood abuse and neglect and anxiety and depression later in life. Children with documented histories of abuse and neglect and matched controls were followed up and assessed in young and middle adulthood. Abused and neglected children were more likely to report experiencing inadequate sleep conditions in childhood, sleep problems in young adulthood, and higher levels of depression and anxiety later in middle adulthood. Results revealed significant indirect paths from childhood maltreatment to anxiety and depression in middle adulthood through inadequate sleep conditions in childhood and sleep problems in young adulthood. This longitudinal follow-up of children with documented cases of maltreatment reveals the important role of sleep disturbances in the lives of maltreated children and adults and sleep disturbances in the development of subsequent anxiety and depression.