Asthma causes substantial morbidity and mortality in the United States, particularly among African American emerging adults (AAEA; ages 18-30), but very few asthma programs have targeted this population. Interventions that provide education and address underlying motivation for managing asthma may be most effective. However, face-to-face interventions are often difficult to implement, especially among emerging adults. The purpose of this proposal is to develop an effective mobile asthma management intervention to improve control in AAEA. We will assess the ability of multiple technologic components to assist and improve traditional asthma education. The intervention includes 4 potential components: 1) MES. The Motivational Enhancement System (MES) for Asthma Management is a mobile 4-session intervention utilizing supported self-regulation and Motivational Interviewing (MI). Personalized content is based on each participant’s activity level, daily experiences, and goals. 2) SA. Supportive accountability (SA) is administered by asthma nurses utilizing targeted mobile support (Skype/voice calls) to provide education, promote self-efficacy, and overcome barriers through an MI-based framework. 3) SMS. Text messaging (SMS) provides reminders for asthma management education, medication adherence, and physical activity. 4) PAT. Physical activity tracking (PAT) uses wearable technology to encourage asthma control in order to meet user-defined physical activity goals. Using a multiphase optimization strategy (MOST), we will refine and test these 4 intervention components and combination of components to identify the most effective mobile intervention. MOST is an innovative, cost- and time-effective experimental design that utilizes engineering principles to test behavioral interventions. Participants (N=180) will be randomized to 1 of 6 intervention arms consisting of various combinations of the intervention components. Using factorial design, this experiment is equivalent to conducting multiple pilot randomized clinical trials to evaluate the efficacy of each of the intervention components, yet uses only a fraction of the sample size and resources. At the completion of the study, we will have an empirically- supported mobile asthma management intervention to improve asthma control for AAEA. Participants will be recruited from multiple sites of the American Lung Association Airway Clinical Research Center network and ambulatory care clinics at the Detroit Medical Center. Data collections will occur at baseline, 4, and 6 months. We hypothesize that post-intervention (4 and 6 months), participants with uncontrolled asthma will show clinically-significant improvement in asthma control. We hypothesize that improvements in asthma management behaviors (including physical activity), quality of life, symptoms, adherence, and exacerbations (secondary outcomes) will also be observed.