Adolescents with diabetes are a complex target group for health prevention initiatives for a number of developmental reasons, such as drive for autonomy, lack of acknowledgement of long term effects of unhealthy behavior, and high frequency of sedentary behaviors and poor diets (Arnett, 2007). Developing interventions that adolescents find appealing and acceptable is a challenge. An emerging health area referred to as "mobile health" has begun to address these issues by developing innovative uses of basic mobile technologies (Vital Wave/United Nations Foundation, 2009). A recent review of 14 studies, most related to diabetes management (n=10) and preventive behaviors, suggests that mobile phone-delivered interventions have positive short-term behavioral outcomes (Fjedshoe et al., 2009). A number of obesity prevention studies with adults have informed the use of mobile features (e.g., tailored messages or visual display of goal progress) and include mobile applications for adult weight loss (Patrick et al., 2009) and physical activity monitoring for women (Consolvo et al., 2008). Studies targeting children are few. However, one randomized controlled trial of Sweet Talk, a text-messaging system to support young people with diabetes, reported some success (Franklin et al., 2006). In a randomized controlled trial, 126 children with type 1 diabetes were allocated to either conventional insulin therapy, conventional therapy and Sweet Talk (the text message program), or intensive insulin therapy and Sweet Talk. Text messages were tailored to patient's age, sex, and insulin regimen. Compared to conventional treatments, automatic daily text messages (info, tips, support) with weekly reminders about personal goals increased self-efficacy and adherence to diabetes management; overall acceptance rates of Sweet Talk were high (82% felt the program improved self-care; 90% wanted to continue receiving messages). Studies such as these prompted the development of BodiMojo, a mobile phone health application to address healthy nutrition, physical activity, and positive body image. BodiMojo will be tested in the current study with up to 90 adolescents with diabetes to determine feasibility and adherence to lifestyle goals, and to examine changes in self-efficacy. It is hypothesized that the experimental participants will report higher self-efficacy for healthy eating and physical activity, and greater adherence to lifestyle goals, compared to control participants. It is also anticipated that the study procedure, design, and intervention will be found to be feasible. In addition, our group at Joslin has previous experience utilizing text message reminders in adolescents and young adults with type 1 diabetes and demonstrated its acceptability and ease of use (Hanauer, 2006).