Formative research was conducted in the Republic of the Marshall Islands to help develop a diabetes prevention intervention. Methods included in-depth interviews, semistructured interviews, and direct observation of household behaviors in urban and remote settings. Foods were classified into two main conceptual spheres: foods from the islands/Marshallese foods and imported/American foods. Diabetes (nanimij in tonal) is a highly salient illness and is believed to be caused by foods high in fat and sugar, consumption of imported/American foods, family background, and the atomic bomb testing. Physical activity and eating a traditional diet were viewed as important for preventing diabetes. The traditional belief system links a large body with health, and a thin body with illness; however, perceptions are changing with increased acculturation and education about the health risks of obesity. These findings were used to develop a diabetes prevention home visit intervention currently being implemented and evaluated in Marshallese households.This article presents formative research on the prevention of non-insulin-dependent diabetes mellitus (NIDDM) in the Republic of the Marshall Islands. NIDDM is a major cause of debilitating morbidity and mortality in industrialized countries and increasingly in nonindustrialized countries. As the onset of diabetes in the nonindustrialized world is linked with lifestyle changes associated with the globalization of the world economy and acculturative Western influence, effective primary prevention strategies are desperately needed.1,2 Unfortunately, interventions aimed at the primary prevention