The primary characteristics examined included physical features of the housing sites (e.g., building size and accessibility to outsiders), socioeconomic characteristics of the resident populations (e.g., their proportions of single-parent, low-income, welfare recipients and their ratios of teenagers to adults), and security practices of housing management and local police. Utilizing interviews with residents, physical site surveys, police and housing authority records, and interviews with community, police, and housing officials, researchers collected extensive data on 63 housing developments in Newark, N.J.; St. Louis; and San Francisco. Path analysis was used to test a causal model based on 'defensible space' hypotheses concerning the significance of the relationship between features of the physical environment and the levels of crime victimization, fear, and instability. More specifically, the report tests the defensible space predictions that a housing site's physical characteristics (in this case, building size and accessibility) will effect its levels of crime (in this case, burglary and robbery/assault victimization), fear, and instability not only directly, but also indirectly, through their impact on the attitudes and behavior of its residents (their sense of control over the public areas outside their apartments and the frequency with which they utilize and interact with other residents in these areas). Findings provide some evidence in support of the two major defensible space principles: (1) the physical features of a housing site were found to be directly (and positively) related to its levels of burglary victimization, fear, and instability, with 'building accessibility' related to burglary rates and 'building size' related to fear and instability; and (2) one physical feature--building size--was also found to be related to crime victimization and fear indirectly, through its association with residents' 'sense of control' over their living area. The report concludes that improvements in the physical design features of Federal housing are the key to achieving more secure and stable residential communities. Recommended physical changes include security features which decrease building accessibility to outsiders and housing designs which limit the number of units per building. Some tabular data, causal model figures, and bibliographic references are included. For a complete report of the research, see NCJ 71094.