Background: Obesity prevention efforts typically involve changing eating and exercise behaviors as well as the physical and social environment in which those behaviors occur. Due to existing social networks, worksites are a logical choice for implementing such interventions. Purpose: This article describes the development and implementation of a peer helper intervention, which was part of a multicomponent obesity prevention program conducted at a hospital worksite. It also presents qualitative evaluation findings of peer helper perceptions, roles, and institutional outcomes. Methods: Fifty-one male and female employees were recruited to promote healthy eating and physical activity amongst their peers. They received health and communication skill-building training. Semistructured interviews were conducted with 20 peer helpers to evaluate this component of the intervention. Results: Findings showed that peer helpers took on many helping roles, became effective role models, and contributed to creating health-promoting social and environmental changes at work. Discussion: We found evidence for synergies between the peer helper component and other components of the campaign and present recommendations and questions related to best practices for peer helper interventions at worksites. Translation to Health Education Practice: Training on the use of peer helpers and the incorporation of peer helper components into interventions is needed.