Smartphone applications (apps) may be well-suited as a low cost adjunctive tool for increasing the adherence of individuals to psychotherapy treatments which may subsequently increase symptom reduction and improve clinical outcomes. Apps offer the opportunity for real-time tracking of behavior and have the ability to provide prompt feedback and reminders in a convenient, readily available technology. The immediacy and convenience of apps may be responsible for the observed improvements in adherence on the part of the patients relative to traditional paper-and-pencil tracking and practice of skills taught in psychotherapy. These features are relevant to behavioral activation (BA) protocols, the effects of which are often attenuated by failure to adhere to regular practice and tracking of behavior. The Mood Coach app is a BA protocol developed to provide a convenient means of planning and tracking activity, and monitoring mood responses to scheduled increases in activity. This project evaluates the utility of this app as an adjunct to standard BA treatment. The investigators predict that participants assigned to the BA+app condition will demonstrate greater adherence to the BA treatment compared to the standard BA condition. The investigators also predict that the participants in the BA+app condition will report greater satisfaction with the app compared to the standard BA protocol that utilizes paper and pencil materials.