The model was based on the research of Grasmick and colleagues and used the RAND-UCLA data set used by Longshore and colleagues. The proposed one-factor solution consisted of six scales: impulsivity, simple tasks, risk seeking, physical activities, volatile temper, and self-centeredness. This self-control scale was both similar and dissimilar to the one used by Longshore and colleagues. The analyses for males and females revealed that the factor structure of the self-control scale was completely invariant across gender groups and thus that the scale was equally reliable across gender groups. The scale was also an equally valid predictor of crimes of force and fraud across gender groups. Findings supported the unidimensionality component of self-control in Gottfredson and Hirschi's general theory of crime. The scale also appears to be capable of tapping into the components alluded to by Gottfredson and Hirschi even in heterogeneous samples of drug-using offenders and should be used in future studies to test criminological theories. At the same time, this research, coupled with findings from Arneklev and colleagues and Longshore and colleagues suggest that the inclusive self-control scale is not as predictive as are some of its components; this finding differs from the Gottfredson and Hirschi concept that is clearly organized around six components. Future researchers should develop various methods of measuring self-control in both attitudinal and behavioral forms and should then assess them in varied samples. Tables, footnotes, and 30 references