A combination of individual-level and county-level data is used to estimate an economic model of crime for young adults similar to that used by Becker (1968) and Trumbull (1989). In order to estimate a model of crime in which both individual-level and county-level data are used, it is necessary to take account of the bias introduced by using aggregate-level data in conjunction with individual-level data. In order to eliminate this bias, a technique derived by Moulton (1990) is employed. Results from a logit regression model indicate that race, sex, and peer pressure have statistically significant effects on the probability that a young adult will commit a crime. Results also suggest that police presence, as measured by county-level per capita police expenditures, does not deter young adults from committing crimes.