Background: Although studies have shown that school-based obesity interventions can be effective, little is known about how to translate and implement programs into real-world school settings. Methods: Semistructured interviews were conducted in spring 2012 with 19 key informants who participated in a multifaceted childhood obesity intervention involving school nurses and wellness coordinators in 6 school districts and over 100 schools. Results: The intervention changed form according to the needs and interests of the school districts. Despite funding support, schools and nurses had little capacity to address childhood obesity without the help of the coordinator. Initiating programs at the beginning of the school year was particularly difficult for schools. Applying for grants from internal and external sources and assisting with planning and logistics for wellness activities were significant activities of the coordinator. Although some school personnel and families preferred a focus on wellness rather than obesity, those working with individual at-risk children and families found the experience especially gratifying. Conclusions: In contrast to controlled studies, real-world implementation of obesity interventions in schools that are intended to create sustained change requires flexibility in intervention design, timing, and personnel. A single change agent focused on obesity-related activities was essential to success. (Contains 2 tables.)