The purpose of this research project was to assess if podcasting could be an effective way to deliver a weight loss intervention. This dissertation followed three aims. Aim 1 consisted of a content analysis of weight loss podcasts (N =13) and surveys with weight loss and physical activity podcast show hosts (N =13) and listeners (N = 22). Podcasts had an average accuracy score of 19.5 (range 15.5 - 22) out of 25. The majority (91%) of listeners reported making at least one healthy change as a result of listening to podcasts. The purpose of Aim 2 was to explore differences in how people process information on weight loss either through reading text on a Web site or listening to the information via podcast. Participants were randomly assigned to view a Healthy Weight Web site (N = 20) or listen to a Healthy Weight podcast (N = 20). Participants completed questionnaire items and had skin conductance (SCL) levels measured. There was no difference in SCL levels between the groups; however, the Web group reported greater ease of navigation and user control and found the intervention to be less novel than the podcast group. Aim 3 consisted of a randomized controlled trial comparing a control podcast to a weight loss podcast based on Social Cognitive Theory (enhanced podcast) for 12 weeks. Enhanced group participants (n=41) had a greater decrease in weight (-2.9 ± 3.5 kg enhanced group vs. -0.3 ± 2.1 control group; P < 0.001 between groups) and BMI (-1.0 ± 1.2 kg/m2 enhanced group vs. -0.1 ± 0.7 kg/m2 control group; P < 0.001 between groups) than the control group (n=37) and had greater weight loss-related knowledge (P < 0.05), elaboration ( P < 0.001), and user control (P < 0.001) and less cognitive load (P < 0.001). The results of this dissertation project suggest that a well-designed, theory-based podcast may be an effective way to promote healthy weight loss. More research is needed to see if podcasting can be as effective at helping people with health behavior changes as other electronic media, such as the Web