The goal of this two-year R34 treatment development grant is in response to RFA-MH-13-061 (Harnessing advanced health technologies to drive mental health improvement) to develop a mHealth application that will both advance theory in and clinical practice guided by the DADR model of HW implementation. Specifically we aim to utilize mHealth to improve the "Design" and "Do" process of HW within the context of the Family Groups for Youth with Behavioral Difficulties (MFG) intervention, an EBT for DBDs in youth and their families who seek assistance at outpatient mental health clinics in urban communities. To date, efforts at utilizing mHealth within the context of HW have been minimal and have not taken a systematic, theory-driven approach, thereby limiting the advance of knowledge and clinical application. Through utilizing self-determination theory as a guiding framework and integrating principles from the field of "gamification" and goal-setting, the aim is to develop a two-component MFG mHealth HW application (My MFG). The first component focuses on delivering MFG HW via a highly engaging, multiplayer, interactive, cooperative, and skill-building game platform aimed at improving the "Design" and "Do" process. The second component focuses on targeting factors putatively related to poor HW implementation within the "Do" process.