Although it is expected that GPS technology provides the capability for near real-time tracking of an offender's location and movement in the community and that alerts would primarily indicate noncompliance with geographic and temporal restrictions, findings indicate that responses to nonviolation alerts due to underdeveloped GPS technology consumed a significant proportion of an agency's resources that could be better used in other case-management activities. A secondary impact of the significant number of nonviolation alerts is the possibility for probation officers to become complacent about the urgency of alerts that constitute real violations. The legislative intent of the mandated GPS monitoring of adult sex offenders in the community is to deter offenders from reoffending. To some extent, this expectation is supported by the relatively low rates of genuine area and time violations. A limited strategy for improving the cost-effectiveness of a GPS program is to decrease unnecessary or unintentional alerts, thereby reducing the levels of staffing and financial resources allocated for response to "false" alerts; in turn, the resources dedicated to case management activities should be increased. Thus, much of the improved cost-efficiency of any GPS monitoring program is directly related to the need to address the intrinsic limitation of GPS equipment and software capabilities. Study data were obtained from official data provided by the Maricopa County Adult Probation Department, which serves the Phoenix metropolitan area, and from semi-structured interviews with community corrections stakeholders in the jurisdiction. The study encompassed the entire population of sex offenders in Maricopa County who were sentenced to probation as part of their sentence after November 1, 2006, and who were subject to mandatory GPS monitoring. 5 figures, 1 table, and 18 references