Over the last two decades, mandatory release has become the dominant prison release mechanism. States and the Federal system have moved away from the practice of discretionary release towards “tough-on-crime” sentencing laws. The term mandatory release refers to the automatic discharge of a prison inmate after serving a specified term in prison. Utilizing the year 1995, which represents the point at which there were approximately equal numbers of prisoners released under discretionary and mandatory schemes nationally, this study compared the outcomes of discretionary versus mandatory release in relation to lengths of time served, percent of time served, and success between those inmates released via mandatory and discretionary schemes. National data were used from the U.S. Department of Justice, Bureau of Justice Statistics (BJS) and the National Corrections Reporting Program (NCRP). Results of the analysis indicate that of the national sample of offenders released in 1995, those released under discretionary systems served longer terms of imprisonment than those released under mandatory schemes. Similarly, those released discretionarily were more likely to successfully complete their term of parole supervision than those released under mandatory laws. The strongest conclusion drawn from this study suggests that discretionary parole release is associated with longer prison terms served and greater parolee success, as measured by type of parole discharge. Tables, references