The science of effective offender rehabilitation remains a very young field: dominated theoretically and empirically by the work of a small group of Canadian psychologists. Their achievements include the 'what works' research literature, and the RNR model of offender rehabilitation. First disseminated in 1990, over the following 20 years, the Risk, Need and Responsivity Principles became the core of the theoretical framework used in those correctional systems around the world that use science as a basis for offender rehabilitation. This paper evaluates the strengths and weaknesses of the RNR model as a Level I rehabilitation framework. It proposes that unrealistic expectations and mistranslations of the model into practice are contributing to concerns about its validity and utility, and stifling needed innovation in the development both of mid-level treatment resources, and of RNR-adherent interventions. It concludes that although the RNR model's empirical validity and practical utility justify its place as the dominant model, it is not the 'last word' on offender rehabilitation; there is much work still to be done.The scientific study of criminal justice interventions has a short history, from which the first publications on 'the RNR model of offender rehabilitation' emerged little more than 20 years ago. Founded on three core principles of offender classification-risk, need, and responsivity-today the RNR model remains the only empirically validated guide for criminal justice interventions that aim to help offenders to depart from that system.Despite the progress made, the RNR model and its growing knowledge base have had limited impact internationally on correctional responses to offenders. The highly emotive and politicized nature of law-and-order issues in our communities can leave little room for the influence of science. Instead, 'truthiness'-judging the validity of ideas by their subjective appeal, without reference to facts, logic, or data (Colbert, 2005) -may prevail. Even in nations that both commit criminal justice resources to rehabilitation and that have adopted the model as a matter of policy, the scope and impact of potentially effective interventions is small compared to the systemic resources dedicated to ineffective but 'true' approaches, such as increasingly severe and diverse forms of punishment and