Rurality is often viewed as presenting challenges to community sustainability, well-being, and equity. To address the unique challenges of rural areas, policies and practices have been designed specifically for application in places designated as “rural”. Yet what is “rural”? Some recent measures of rurality have gone beyond a dichotomous rural-urban divide conceptualization of rural communities. However, most measures still emphasize proximity to metropolitan areas and population density as the primary components of rurality. Few studies consider the critical role that services and amenities play in the life of a community. We suggest a new measure based on the concept of sustainable development that integrates measures of environmental, social, and economic resources. We present the Community Assets and Relative Rurality index for census block-groups in the coterminous United States and illustrate how this measure is consistent with existing measures of rurality yet offers additional insight into issues of sustainable rural development.