The historical review of risk-assessment instruments focuses on the current internationally used series of risk/need assessment tools named the level of Service Inventory (LSI). The LSI was originally developed in Ontario, Canada, in the late 1970s and quickly became accepted in other countries. The authors caution that the LSI/CMI, as it is being used in Canada, is an example of how risk/need assessment is being used to structure and limit which treatment programs are being offered and where institutional resources are allocated. The issue of concern is whether the instrument is sufficiently objective to have this kind of pervasive power. Versions of the LSI are used at several stages of criminal justice processing to assess men, women, and juvenile offenders for presentencing and sentencing decisions, as well as for institutional placement. They are used in probation/parole decisionmaking and in jails and prisons to determine security classification and program needs. The LSI is also routinely readministered in the course of a custodial sentence to inform administrative decisions in case management, transfers, program completion, and release. Over the course of several modifications, 10 versions of the tool exist. This paper groups the various versions of the instrument into two main categories: the LSI group, which was initially developed for supervision purposes, and the newer Level of Service/Case management Inventory (LSI/CMI) series or tools, which are designed for use in treatment interventions. 59 references