Abstract
This paper attempts to discriminate between deterrence, incapacitation, and measurement error as explanations for the negative empirical relationship between arrest rates and crime. Measurement error cannot explain the observed patterns in the data. Incapacitation suggests that an increase in the arrest rate for one crime will reduces all crime rates; deterrence predicts that an increase in the arrest rate for one crime will lead to a rise in other crimes as criminals substitute away from the first crime. Empirically, deterrence appears to be the more important factor, particularly for property crimes. (JEL K42)