The New Jersey Comprehensive Immunization Project (NJ-CTP) is a computerized immunization registry being established in the state of New Jersey. The Leonard Davis Institute of Health Economics at the University of Pennsylvania and the University of Medicine and Dentistry of New Jersey are collaborating on a cost-effectiveness analysis of the project. This article presents a Net Present Value methodology for aggregating and analyzing all economically quantifiable aspects of the NJ-CIP. Baseline data have been collected for the analysis of the project. However, full project analysis will not be possible until the expected collection of postintervention data. The full cost-effectiveness evaluation is expected to be completed by February 1, 1997. Cost-effectiveness will be assessed by comparing changes in immunization rates with the total economic impact of the NJ-CIP. Changes in immunization coverage will be assessed using four different measures of immunization rates to provide insights into immunization coverage. The four immunization coverage measures are Lifetime Optimally Immunized (LOI), Adequately Immunized (AI), Percent of Life Undervaccinated (PLUV), and CASA Age Appropriate Immunization (CASA AAI). The article outlines potential benefits and costs associated with the project, such as increased immunization rates, reduced loss in parental income, and registry costs. The integration of this information into the cost-effectiveness analysis is also described.