The experimental psychology approach was used to examine the judgments of individual persons on tasks designed to provide evidence about underlying decision processes, i.e., to discover the chief motivation behind a prospective offender's choice to commit, or refrain from committing, a crime. The assumption upon which the present analysis is based is that criminals make a few simple comparisons and partial examinations of crime opportunities, and that the relevant data for studying responses to crime opportunities are individual judgments rather than aggregate statistics. Adult and juvenile male subjects, offenders and nonoffenders, evaluated three-outcome gambles consisting of four dimensions: (1) the probability of a successful crime, (2) the money to be obtained if successful, (3) the probability of arrest, and (4) the penalty if caught. The subjects based their judgments primarily on a single dimension, although dimensional preferences varied greatly among the types of subjects. Money was found to be the most important dimension, followed by penalty, probability of success, and probability of arrest. These findings support the proposed approach and suggest that making crime less profitable in comparison to noncrime opportunities may have stronger effects on crime rates than increasing the likelihood and severity of punishment. Yet the controversy between those who advocate certain and severe punishment as a crime deterrent, and sociologists and psychologists who recommend different approaches, is still continuing. The text is illustrated with graphs, and 18 references are appended.