Sustainability has been viewed as a commitment to protection of the environment, responsible economic growth, and promotion of equity—the well-known three “Es.” The third “E,” however, is not as well understood or promoted as the other two. This article considers what equity means as a dimension of sustainability and examines what local governments are doing to advance social equity. Reviewing the results of a national survey in 2010 made it evident that most cities and counties are doing little related to equity. A followup survey was conducted involving two groups of governments identified in that survey—one group was active in social equity and a second was active in sustainability overall but was doing little related to equity. The results reveal the widespread differences between the goals and agendas pursued by the two groups of governments. From the survey respondents, nine governments with broad-ranging activities to promote equity were identified to be the subjects of case studies. Engaging citizens, cooperation between cities and counties, partnerships with nonprofit organizations, and recognition of the value of diversity were qualities shared by the governments in the case studies. Building on and expanding the theme of the livable cities initiative sponsored by the U.S. Department of Housing and Urban Development, Environmental Protection Agency, and U.S. Department of Transportation, the research indicates that sustainability entails efforts to improve the livability of communities in the present and to build the social, environmental, and economic viability of communities for the long term.