The overarching objective of this proposal is to conduct a randomized trial to evaluate the effectiveness of the Individual Well-Being Navigator (Iwin) mobile application, a substance abuse prevention and well-being enhancement program designed specifically for military personnel. Iwin provides an innovative, tailored mobile application using best practices in behavior change science and innovative technology to assist military personnel in preventing substance abuse and enhancing well-being by providing them with the most appropriate intervention content at the right time. It integrates Transtheoretical Model of Behavior Change based tailoring, in app messaging, stage of change matched activities, and engaging game-like features in a cutting edge multiple behavior change program. The efficacy of the Iwin program will be determined by tests of statistical significance indicating that participants in the Treatment condition had lower scores on an index of substance use and other behavioral risks. The overall design is a 2 group (treatment and control group) by 3 Occasions with repeated measures across occasions.