The developed model, which is designed for empirical testing, draws heavily upon the two basic variants of the economic model of crime: the models of Isaac Ehrlich and of Block and Heineke. In the empirical testing, the dependent variables were the number of arrests per month 'free' and the number of convictions per month 'free' (actual number of arrests and convictions adjusted by the varying amounts of time free by the men in the sample during the followup period). The results indicate that both the expected certainty and severity of punishment deter criminal activity in a number of instances, and a 1 percent increase in certainty has a greater effect than a similar increase in severity. Moreover, certainty of punishment has a greater effect for relatively minor offenders, and severity of punishment has a greater effect on offenders committing crimes against persons. Also, higher legal wages tend to decrease the expected number of arrests or convictions but only significantly for nonserious offenders. Overall, strength and consistency of the evidence supporting the deterrent effect of high probabilities of apprehension and punishment is much greater than that supporting the deterrent effect of longer prison sentences. However, the deterrent effect of criminal justice sanctions varies markedly across crime types. Footnotes, 36 references, and 4 tables are provided.