The ability of a coalition to sustain its impact in a community over time is a vital element of success. Four sustainability strategies have emerged among Allies Against Asthma coalitions: (a) resource development; (b) institutionalization; (c) system change, including policy change; and (d) capacity building. Although it is too early to determine their ultimate success, a number of important lessons have been learned about the coalitions' sustainability efforts: (a) sustainability must be considered as a planning principle, (b) data demonstrating success will enhance efforts to sustain worthy efforts, (c) ongoing communication and relationship building are critical elements of sustainability, (d) considering sustainability can help guide membership recruitment efforts, (e) coalitions with previous asthma and/or coalition experience may be better prepared to address sustainability within a short project period, and (f) although difficult to fund, the coalition infrastructure itself is key to successfully sustaining outcomes and activities.