Self-control theory contends that people differ in their ability to control impulses for immediate gratification because of differences in socialization, mainly before puberty. Those with low self-control have a much greater probability of criminal behaviors than do those with high self-control. The theory implies that the effects of self-control are similar in all circumstances. This research tries to determine the extent to which self-control accounts for gender and age differences in crime, and whether the association between self-control and crime differs among gender and age categories such that they serve as contingencies for the operation of self-control in affecting crime or deviance. Data were used from a survey of the residents of a southwestern city, concentrating specifically on gender and age variation in self-control. A total of 350 respondents, age 18 and over, were selected by simple random methods. A 23-item factor-based cognitive scale, behavioral self-control measure, and self-control index were used as measures. The results show that for every crime index in the study, males scored significantly higher than females. Age was negatively associated with all four of the crime/deviance indexes. The claims of the theory that self-control is the main variable leading to criminal/deviant behavior are strengthened by some of the results, but the parallel claims that self-control accounts similarly for misbehavior in all of its variations and distributions appears to be overly optimistic. Support for the hypotheses examined here appears to depend on how self-control is measured. 6 tables, 2 notes, 65 references