Both the stereotypes held by investigating officers and the clinical literature assume that child molesters have distinct characteristics. These are generally expected to be shown in a prior-offense history of assaults on children and sexually deviant behavior. Another assumption is that there is an escalation of offending, with less serious crimes being precursors of more serious ones. To test these assumptions, this study examined the prior criminal convictions, if any, of 416 convicted offenders who had committed sexual offenses against children between the ages of 5 and 12 in the Lancashire Police area (England) during 1987, 1988, and 1989. Of the 183 (44 percent) of offenders who had previous convictions, 72 (17 percent) involved indecency. Previous convictions for theft, burglary, and violence were all much more frequent. Neither do the results support the hypothesis that serious offenders have progressed from less serious offenses against children. A criminal opportunist model is proposed as of more value for guiding investigations than the existing stereotypes. Under this model, child molestation has less to do with pedophilia than with the offender's tendency to commit a criminal act against a weaker individual found in a vulnerable situation. 3 tables and 11 references