The containment approach recommended for the management of sex offenders emphasizes sex offender treatment as an important program component. This recommendation implies that sex offender treatment is effective. However, an important debate exists over how to interpret the findings of sex offender treatment outcome studies. The debate centers in the difficulty of conducting effectiveness studies with the scientific rigor required to answer the question confidently. Although some researchers believe that existing studies permit an inference of a qualified yes regarding treatment effectiveness, other researchers maintain that, without adequate research designs, no is the only scientifically responsible answer. Nevertheless, certain behavioral interventions appear to affect certain classifications of offenders positively. Clearly, empirical work on sex offender classification is needed to match interventions to offender needs. Better measures of treatment effectiveness and continuing evaluations are also needed. If sex offender treatment were scientifically determined to be useless, it would be unethical and irresponsible to make it mandatory for sex offenders. Footnotes and 24 references