Major sections of this report address EM uses in offender monitoring, the conceptual system framework, State and local EM practices, ways to increase the efficiency of offender monitoring, the operational impact of EM, and cost considerations. The use of EM systems in community corrections has become more widespread over the past 15 years due to many State and local jurisdictions facing directives to implement this technology as a condition for offenders' release from confinement; however, there is wide variation in the applications and in the degree to which they have been successfully implemented. Benefits of EM include the tailoring of monitoring approaches to individual offenders, providing an alternative to incarceration in managing high-risk offenders, improving the integration of ex-offenders into the community, and quick detection and response to offenders in high-risk or prohibited locations. Although there is potential for improving long-term outcomes for managing offenders with EM within an overall strategy of behavioral modification, one well-designed study found that the effectiveness of EM supplemented with treatment depends on the offender's risk level. Generally, studies of the performance of EM systems have found significant cost advantages when compared with more traditional approaches to offender supervision. Still, system improvements are needed for the reliable and accurate tracking of clients indoors, underground (subways), in inclement weather, in tall buildings, and in rugged terrain. 2 figures, 2 tables, 50 references, and appended detailed information