The "risk" principle suggests that offenders at higher risk for reoffending will benefit most from higher levels of intervention, including high-intensity treatment, and that lower risk offenders should receive minimal, routine, or no intervention. The "need" principle proposes that only those factors associated with reduction in reoffending (i.e., criminogenic needs) should be targeted in interventions. The "responsivity" principle holds that correctional programs should match offender characteristics, such as learning style, level of motivation, and individual personal and interpersonal circumstances. The RNR model of offender rehabilitation as applied by correctional services throughout the world has resulted in reduced reoffending rates and safer communities; however, despite its many virtues, the model has been criticized because of perceptions of its theoretical, policy, and practice weaknesses. The authors argue that one of the major reasons for these problems lies in the way the RNR model has been developed and applied. The emphasis has been on the practical use of the three major principles of risk, need, and responsivity. Therefore, the theoretical underpinnings of the model have been underdeveloped and insufficiently integrated with the practice components. In order to remedy this difficulty, the authors have reconstructed the RNR model by using a three-level structure: overall aims, principles, and values; etiological and methodological assumptions; and practice implications. The result is a more integrated, systematic theory of rehabilitation that improves guidance for therapists. 3 figures and 49 references