Community-based efforts to revitalize neighborhoods have had a significant impact on many the of nation's inner cities. However, the community development corporations (CDCs) leading these efforts are increasingly called upon to demonstrate their impacts in quantitative, economic terms. This research focuses on two questions: Can the impact of community-based homeownership efforts be quantified in terms of economic indicators? Are there identifiable thresholds of development at which changes in these indicators accelerate?  Five case studies of urban neighborhoods -- in Kalamazoo, Houston, Seattle, and Washington, D.C. -- are analyzed. In each of these cases, community-based organizations, primarily CDCs, created a significant amount of affordable for-sale housing. Data were gathered on the timing and location of this housing development and the effect of this development on three indicators, residential real estate markets, commercial activity, and crime rates.