 The focus of this study is on identifying how Interpersonal Psychotherapy for Adolescents IPT-A with depression works to change sleep and related biological markers found in saliva, namely cortisol and pro-inflammatory cytokine levels. The long-term goal of this project is to understand the biological mechanisms of recovery from depression in order to assist in selecting and guiding personalized psychotherapeutic interventions with the highest likelihood of success for individual adolescents with depression. 