Background: Medical schools need to teach future physicians about health literacy and patient-doctor communication, especially when working with vulnerable communities, but many fall short. In this article, we present a community-based, service learning experience over one academic year during the pre-clerkship portion of medical school as an innovative and successful model for medical students to learn about health literacy and practice effective communication strategies. "Eat Healthy, Stay Active!" (EHSA) is a 5-month pediatric obesity intervention designed for Head Start children, their parent(s), and staff. We hypothesized students' attitudes, knowledge, and skills confidence regarding healthy literacy and patient communication would improve from baseline after receiving training and serving as family mentors in the EHSA intervention. Methods: First- and second-year medical students were trained through a series of didactics and then partnered with Head Start children, parents, and staff to help educate and set goals with families during the EHSA intervention. Medical students were given a pre- and post-intervention survey designed to measure their attitudes, knowledge, and skills confidence regarding health literacy. The pre-survey was administered before the first didactic session and the post-survey was administered after the conclusion of the EHSA intervention. We compared students' pre- and post-intervention responses using paired t-tests. Throughout the project, the medical students were asked to complete a set of open-ended journal questions about their experiences. These responses were examined using qualitative, thematic analyses. Additionally, the Head Start parents and staff were asked to complete a survey about their experience working with the medical students. Results: Participant (n=12) pre- and post-surveys revealed that medical students' attitudes about the importance of health literacy were ranked highly both pre- and post- intervention. However, knowledge and skills confidence regarding health literacy showed statistically significant improvement from baseline. Journal entries were categorized qualitatively to demonstrate medical students' insight about their growth and development throughout the project. Survey results from Head Start parents showed medical student participation to be highly valued. Conclusion: Providing medical students with a service learning opportunity to work with individuals with low health literacy in their pre-clerkship years increased students' knowledge and skills confidence regarding health literacy and communication. (author abstract)