The authors develop a model that maximizes perceived safety by allocating a given budget between public security and private protection. Additionally, the article examines the effects of community size on the issue examined and on the level of negative externalities caused by the consumption of private protection. The level of negative externalities of private protection is shown to diminish with community size. The theoretical model suggests that as the size of a community increases, a shift from public to private provision of security occurs. At the same time, for a given level of total (public and private) outlays, the safety level as perceived by an individual diminishes. In addition, there is less need and desire to cooperate in the provision of private security. In small communities, the level of public security inputs is low because per capita cost is high, although their effectiveness is also high. As population increases, per capita cost of public security diminishes, more police are used, and the level of per capita safety increases. In large communities, the effectiveness of public security diminishes at a faster rate than do the gains realized by cost sharing. This implies that individuals shift toward greater use of private protection inputs. 1 table and 14 references