The mobile platform provides exciting possibilities for the promotion of health behaviors through mobile health (mHealth) app. It enables passive data collection, timely and personalized intervention delivery, and anytime/anywhere accessibility to self-monitoring and self-management tools. Despite these promising developments, a critical issue remains: the law of attrition (Eysenbach, 2005). That is, a large proportion of users abandon mHealth apps and wearables quickly and after minimal use. As a result, there is a pressing need to develop strategies to retain users, or to sustain user engagement. To address the issue of attrition in mHealth apps, we have developed an engagement wrapper (ewrapper). ewrapper is a mobile app that integrates a collection of engagement strategies and “wraps” around existing/inherent mHealth app to enhance engagement in the target health behavior(s). We are in the process of planning a pilot study to investigate the feasibility, acceptability, and potential efficacy of ewrapper in the context of a mobile intervention that supports self-monitoring of dietary intake and physical activity among ethnic minority overweight/obese young adults. Specifically, a two-arm pilot RCT will be conducted, whereby all participants will receive a mobile app and a Fitbit band to support self-monitoring of physical activity and dietary intake. Participants will be randomized with equal probability to either (a) the mHealth self-monitoring support alone (control condition) or (b) the mHealth self-monitoring support with ewrapper (experimental condition). Within the experimental condition, participants will be micro-randomized multiple times per day at particular decision points of scientific interest to various engagement strategies; this data will be used to further inform the selection and adaptation of real-time engagement strategies in the eWrapper.