This study examined the relationship between child maltreatment, depression severity, and cortisol responding in adolescents. Cortisol is a hormone that has been implicated in depressive disorders. This study utilized a psychological challenge paradigm entitled the Trier Social Stress Test to examine cortisol responses (TSST; Kirschbaum et al., 1993). Participants included 71 individuals ages 12 to 21 years recruited from a mid-size community in Ontario. The sample included adolescents with depression and those without depression. All participants received: a diagnostic interview to evaluate the presence of current/past mental health diagnoses; a questionnaire assessing depression symptoms (BDI-II); an interview to assess stage of development and history of child maltreatment. Saliva was collected from participants at numerous time points: before, during, and after the administration of the TSST, in order to examine cortisol responses over time. Of the 71 participants, 26 adolescents reported a history of child maltreatment. Results indicate that among those with mild/moderate depression severity, a history of childhood maltreatment is associated with significantly higher and more prolonged cortisol levels in response to the TSST. This study has significant implications for our understandings of the biological pathways to depression, and suggests that individual differences in both depression severity and maltreatment history should be considered in all studies examining biological aspects of depression.