A multiplicative term involving low self-control and crime opportunity was chosen to test the interaction argument. A factor analysis of items designed to measure low self- control was consistent with the contention of Gottfredson and Hirschi that that trait is unidimensional. The prediction that the multiplicative term for the interaction of low self- control and crime opportunity will have a significant positive effect was upheld. Evidence of the second prediction that the magnitude of the effect of the interaction should be greater than the main effect of low self-control was less definitive but still generally supportive of the theory. The results for both force and fraud fail to support the third prediction that crime opportunity will not have a significant main effect. For fraud, the main effect of crime opportunity was nearly equal in magnitude to the interaction effect, and the difference between the two was insignificant. The findings for force were more inconsistent with the prediction. The data show crime opportunity as defined by Gottfredson and Hirschi to be important in providing the condition under which low self-control has its primary effect on crime but also as a significant predictor of fraud and force independent of its interaction with low self-control. 6 notes, 2 tables, and 55 references