An adaptive intervention (AI) is an intervention design that seeks to address not only the unique, but also the changing needs of individuals as they progress through an intervention. AIs are intended to guide the efforts by therapists, teachers, and other clinical and/or academic staff to provide individualized intervention to individuals in practice. A Just-in-time Adaptive Intervention (JITAI) is a special form of an adaptive intervention that often capitalizes on advances in wireless and mobile devices to address the rapidly changing needs of individuals. In recent years there has been increased interest in developing empirically-informed AIs and JITAIs to address a wide range of behavioral health issues, including depression, anxiety, alcohol use, substance use and sedentary lifestyles. These intervention approaches play an important role in various domains of psychology, including clinical, educational, organizational and health psychology. The goal of this workshop is to provide an introduction to AIs and JITAIs, and discuss novel experimental approaches for optimizing these interventions.