Background: Maternal depression may be a risk factor for childhood trauma (CT), with resultant offspring development of mood disorders (MD) in adult life. Objective: To verify the relationship between maternal depression (as a risk factor for childhood trauma) and mood disorders in young adults. Methods: The sample was composed of 164 young adults and their mothers. Maternal depression was identified through the Mini International Neuropsychiatric Interview (M.I.N.I.). Mood Disorders in the young adults were confirmed with the Structured Interview for the DSM-IV (SCID), whereas the CT was evaluated using the Childhood Trauma Questionnaire (CTQ). Results: In the group of young adults with MD, individuals who had depressed mothers presented higher mean scores of CT in comparison to the ones who did not have mothers with Depression (p < 0.005). Childhood trauma was also associated with lower social classes (p < 0.005). In the group of young adults without MD, the only variable that was associated with CT was the young adult’s (not) current work (p < 0.005). Discussion: Maternal depression was considered to be a risk factor for CT and MD in young adults. Thus, preventing and treating maternal psychiatric disorders may diminish the risk of offspring childhood trauma, and, consequently, avoid negative effects in the offspring’s adult life.