As the Nation's first rigorous large-scale evaluation of vocational rehabilitation (VR) assistance to persons with severe disabilities, the Project NetWork demonstration will provide a wide range of information to policy-makers, researchers, and other interest groups. The evaluation of Project NetWork addresses two key policy questions: Is it feasible to increase participation in VR services among Disability Insurance (DI) beneficiaries and Supplemental Security Income (SSI) applicants/recipients through a combination of intensive outreach, case management, and enhanced work incentives? Do the interventions tested produce net benefits from the perspective of participants, society, the DI Trust Fund, and the Federal Government, as a whole? The study utilizes a randomized field experiment design to evaluate the net impact of the demonstration on participant employment, earnings, receipt of transfer benefits, social and psychological well-being, and other variables of interest to policymakers. A combination of SSA administrative data, information from the demonstration's onsite management information system (MIS), and in-person interviews (containing a rich array of information on disability, health, and attitudes) supports the evaluation. This article summarizes three aspects of the evaluation: Its experimental and sample design; the methods and data to be used to analyze project benefits, costs, and participation; and the challenges faced during demonstration implementation. It also presents preliminary data on the characteristics of Project NetWork participants and eligibles.