We develop a model of crime in which the number of police, the crime rate, the arrest rate, the employment rate and the wage rate are joint outcomes of a subgame perfect Nash equilibrium. The local government chooses the size of its police force and citizens choose among work, home and crime alternatives. We estimate the model using MSA-level data. We use the estimated model to examine the effects on crime of targeted federal transfers to local governments to increase police. We find that knowledge about unobserved MSA-specific attributes is critical for the optimal allocation of police across MSA's.