Prevention and early detection of HIV infection through counseling and testing is a major part primary and secondary AIDS prevention efforts. The purpose of this study is to evaluate he effectiveness and cost- effectiveness of HIV testing programs and policies. The specific aims are to: 1) Evaluate the prevalence and predictors of HIV test site selection, repeat testing, nd follow.through on intentions to be tested. Both cross- sectionl and longitudinal data on three datasets will be used: the National Health Interview Surveys, the National AIDS Behavioral Surveys, and the Community AIDS Mobilization Project. The study will develop a conceptual model for, and evaluate, individuals' choice of public, private, or home testing; repeat testing; and follow-through on intentions to be tested. Multiple regression analyses will be used to assess the relationship of risk behaviors, knowledge, attitudes and beliefs, sociodemographics, costs and policies to testing behavior. Results will be used as inputs to the study described in Aim #2, and the policy and programmatic implications will be assessed. 2) Evaluate the relative cost-effectiveness and cost-utility of public, private, and home w testing and different testing protocols. Decision analysis will be used to model the choice between public, private, and home testing, and choices between different testing protocols. The cost-effectiveness and cost-utility of testing will be examined by combining data from Aim #1 and other effectiveness data with cost data. Data needed for the analysis will be identified, existing data will be evaluated, and new data will be collected. The study will address policy issues of reallocating resources and the trade-offs involved in testing decisions. The study will pave the way for future analyses by identifying new and existing data sources, developing a model and approach for analysis, determining what data are most important for future research, and demonstrating how economic analyses can be used to evaluate AIDS prevention programs and policies.