Source: (1998) M.A. thesis, Department of Psychology, Carleton University, Ottawa, Canada. Downloaded 9 March 2005.The effectiveness of correctional treatment programs has been extensively debated. Although the earlier literature reviews examining this topic mainly supported an antirehabilitation theme, recent research using meta-analytic techniques has provided positive support for rehabilitation. The present investigation consisted of a meta-analysis conducted on the rehabilitation literature with the goal of providing a more systematic analysis and definition of the principles of risk, need and responsivity. The goal of this project was to provide a comprehensive answer to the question 'what works'. Results indicated that each of these principles play an important role in reducing general recidivism in offender treatment populations. However, only the principles of need and responsivity maintained significant contributions to treatment success when examining violent recidivism. An appropriate treatment variable based on these principles proved highly significant in predicting treatment outcome. This construct maintained its importance when various threats to validity were introduced. Results clearly indicate that rehabilitation produces mild positive effects within an offender population However, if the end goal of the program is to evoke the highest level of behavioral change possible, the principles of risk need and responsivity must be addressed. Author's abstract.