Anhedonia is a risk factor for poor prognosis and suicidality, and yet treatments to date have been relatively ineffective for anhedonia. Based on advances in behavioral and neural science, Positive Affect Treatment was developed to specifically target areas of reward sensitivity that are believed to contribute to anhedonia. These include the anticipation and motivation for reward, the response to attainment of reward, and the learning of associations between actions and reward outcomes. Positive Affect Treatment for Depression and Anxiety: Therapist Guide is intended to be used by clinicians who are familiar with cognitive-behavioral therapy (CBT) generally and with clinical presentation of depression, anxiety and anhedonia. Results show that Positive Affect Treatment not only improves positive mood state but also decreases depression and anxiety. This guide will be an indispensable resource for all practitioners who wish to effectively and efficiently help individuals regain interest and enjoyment in their usual activities while improving their quality of life.