Community-based risk factor modification is today an established approach to chronic disease control and public health practice. This article analyzes the shaping of the North Karelia Project (NKP), an early and influential formulation of the community approach that focused on coronary heart disease prevention in Finland. Instead of targeting only high-risk individuals, NKP aimed to change the culture of the local community. On the basis of archival material and interviews, I first trace the multiple origins of the notion of community in NKP, which combined "internal" factors (local risk factor distribution, the role given to the social environment in chronic disease prevention) and "external" influences (regional origin of the initiative, World Health Organization and national policy concepts of community control and primary health care). Second, I describe the shape of the community intervention in NKP. The project foregrounded social relationships as a way to educate the public and influence norms guiding individual behaviors while subordinating environmental changes of a more structural nature.