This study investigated whether more complex maltreatment experiences predicted higher levels of depressive symptomatology for young adults and examined the role of social support during late adolescence in that association. Specifically, the study tested whether social support had a direct effect on depression and whether it mediated and/or moderated the relationship between self-reported maltreatment and depression in a sample of 513 youth exiting the child welfare system. Indices of maltreatment types (neglect and physical, sexual, psychological abuse) experienced during two periods (precare and during-care) were used in conjunction with a measure of perceived social support (reflecting support availability and social network sufficiency) in negative binomial regression models predicting depressive symptoms. Both precare and during-care maltreatment were associated with depressive symptoms as a young adult. Social support had a direct effect on depressive symptoms as well as moderation and partial mediation effects on the relationship between maltreatment and depression. Social support's buffering effect was stronger for those experiencing fewer types of maltreatment. This buffering effect appears to diminish as maltreatment histories become more complex. (Published Abstract)