A statistically derived tool for predicting the recidivism of offenders released from Canadian institutions, also known as the Nuffield Scale and the Recidivism Prediction Scale, the SIR combines measures of demographic characteristics and criminal history in a scoring system that yields estimates of the chances of recidivism for different groups of inmates. Several studies have examined the usefulness of the SIR. Their various samples include: the post-release recidivism of 2,475 male offenders released from Canadian penitentiaries between 1970-1972; post release recidivism in a sample of 534 inmates released from Federal institutions in 1983 and 1984; a national sample of 221 offenders who successfully completed community supervision or were revoked during 1985; and a random sample of 203 male offenders released from Federal institutions in the Prairie region. All studies reviewed provide generally favorable evidence about the potential utility of the SIR. SIR has demonstrated an ability to forecast the post-release recidivism of Federal inmates and appears to have established its stability over time and with different samples of offenders. 2 figures