Subjects were matched for offense, prior commitment record, age, ethnic group, institution, and parole year. In a comparison with respect to eight categories of parole outcomes over parole periods of 6 months, 1 year, and overall (6 months to 2 years), the TM twins had significantly better parole outcomes than the control twins. The TM group also had significantly more clean parole records and less total prison recidivism (defined as parole revocations or new prison terms). A survey of regularity of TM practice yielded responses from a majority of inmates instructed who were still in prison, and most of these were still practising the TM technique after up to 6 years. (Author abstract modified)