There are four major tenets of the theoretical foundation for the prototypical ISP: focus on the provision of intensive services; prioritize offender needs; exercise a balanced approach to supervision; and focus on results versus activities. Critical factors in program development are needs assessment, staffing, funding, engaging stakeholders, networking with community service providers, and program monitoring and evaluation. ISP's that are most cost effective target high-risk/need offenders. They can benefit the most from the programs provided and also have the greatest impact when their behaviors are modified. Suggestions are offered in this article for how to select such offenders. Critical elements for ISP implementation are small caseloads, an available range of correctional interventions, an objectives- based management system, systematic case review, a system of positive reinforcement, a system of control and accountability, victim restitution, community involvement, and aftercare. ISP program experience is described for New Jersey, Massachusetts, and Colorado. 2 notes and a 37-item bibliography