<qa>  What is the main reason for the onset of unipolar major depression?Early-onset unipolar major depression is linked with considerable morbidity and mortality Birmaher et al., 1996. The goal of this project is to test the efficacy of Behavioral Activation BA; Jacobson et al., 2001 and an integrated version of Behavioral Activation BA Stress Inoculation Coping; BASIC for the short-term psychotherapy of adults with chronic major depression onset before age 18 and a history of early life stress before age 18. Exposure to stress during the developmental years has been linked with early-onset depression Rao et al., 1996, a propensity to generate stress during the life span Hammen et al., 1998, and a greater psychological sensitivity to stress as an adult Post et al., 1992. And while incidence of early life stress is high among depressed adults, there are no behavioral treatments designed to address the unique needs of these individuals. We aim to develop a new treatment for a specific group of depressed patients, namely individuals who report early onset of depression and early life stress. We include the critical elements of behavioral activation and stress reduction strategies to address the avoidance, stress sensitivities, and coping deficits often observed in this population. 