Recently developed behavioral activation interventions have shown promise in effectively treating depression through increasing value-based activity levels that elicit response-contingent reinforcement. This case study highlights the implementation of behavioral activation to a breast cancer patient with major depression and generalized anxiety disorder, applied within the context of a medical center oncology clinic. Following an eight-session behavioral activation protocol, the patient demonstrated notable decreases in self-reported depressive and anxious symptoms and an overall increase in quality of life and medical functioning. These treatment gains were maintained through 6-month follow-up. Consistent with an accumulating literature, these data support behavioral activation as an effective and parsimonious intervention for individuals with depression and concurrent medical problems such as breast cancer. 10.1177/1534650108327474