The prevalent view on depression is that it is a brain disorder. Psychotherapists normally focus on events within the lifespan of a patient and examine proximal (mechanistic) causes of depression (e.g., maladaptive behaviors or irrational thoughts). Recent advances in Evolutionary Psychology, however, propose that low mood has an adaptive function, signaling fitness problems. The P.I.’s own research shows that Darwinian fitness is negatively associated with a variety of psychopathologies, particularly depression, strengthening these arguments. All these point to the hypothesis that interventions on evolutionary (i.e., distal, or ultimate) causes of depression can have therapeutic value. The present study proposes to: a) develop a manual for an evolutionary-driven form of psychotherapy for depression, in which therapeutic interventions focus on ultimate causes and b) conduct a randomized clinical trial to determine the efficacy of such interventions. One hundred depressed subjects will be recruited and randomly assigned to three conditions: a) Waitlist (WL), b) Cognitive Therapy (CT) and c) Evolutionary Intervention (EI). The participants in the CT and EI conditions will receive 12 weeks of cognitive therapy and the proposed evolutionary-driven intervention, respectively. Depression measures will be administered pre- and post-treatment, as well as each therapy session. Outcome depression severity scores will be compared across the three conditions.