Community" in the twenty-first century seems to be everywhere and nowhere. On the one hand, the rhetoric of community is omnipresent, as nonprofit organizations, civic associations, government agencies, and even multinational corporate entities routinely describe their activities to be community-oriented. On the other hand, community in the broader sense of shared interests or solidarities appears to be under unrelenting attack, challenged by sociopolitical forces and intellectual currents that point toward more fragmented social orders. Locating community as a particular field of practice poses similar dilemmas. This article summarizes the broad outlines of the history of "community organization" in the United States, emphasizing both its multiple traditions and the enduring nature of its practical and strategic dilemmas. It provides an analysis of the key intellectual and social challenges facing the field and the different kinds of pressures they may be exerting on the different traditions of community action. Finally, it suggests four "boundarycrossing" areas of activity that cut across the inherited traditions and may represent emerging sources of innovation for community-based action."Community" in the twenty-first century seems to be everywhere and nowhere. Although this state of affairs is hardly unprecedented-community has been lost, found, and rediscovered over the years with disturbing regularity (e.g., Stein, 1960;Sampson, 1999)-the problem is especially pressing today. On the one hand, the rhetoric of community is omnipresent, as nonprofit organizations, civic associations, government agencies, and even multinational corporate entities routinely describe their activities to be community-oriented. Long-neglected inner-city community areas have been rediscovered; new conceptions of communal ties (e.g., social capital) have emerged; new kinds of planned communities are being constructed. On the other hand, community in the broader sense of shared interests or solidarities appears to be under unrelenting