This study classified potential attrition predictors under the domains of risk, need and responsivity (D. Andrews & J. Bonta, 2003). Non-sexual criminogenic needs (e.g. aggression, rule violating behaviors) and responsivity factors (e.g. lack of motivation and denial) were the two main clusters of predictors that correctly classified 95.3% of program completers and non-completers using discriminant function analysis in a sample of high-risk male sexual offenders treated in an accredited inpatient sex offender treatment program. Rapists were more aggressive than other types of sex offenders and were more likely to drop out of treatment. Some studies of predictors of treatment attrition have used offender problem behaviors or psychopathologies to predict attrition and then use the information to exclude offenders from treatment. Others have argued, and we concur, that results of attrition research should not be used to develop an "attrition profile" to exclude offenders from treatment. Predictors of attrition should be seen as markers for program improvement, rather than shortcomings of the offender. Suggestions for program improvements to reduce the rate of attrition, based on results of research, are presented.