The Hilltop Institute prepared this resource guide intended for analysts who plan to integrate data on Medicare and Medicaid service use and costs. The Hilltop Crossover Framework is introduced in the guide as an orienting reference device for linked Medicare and Medicaid claims, and is based on a two-by-two format whereby data are arrayed by category of service - with specific reference to Medicaid crossover claims - in order to highlight the relationships between government programs and service use. The term "crossover" refers to Medicaid claims that reflect Medicare patient liability costs that state Medicaid programs cover on behalf of persons eligible under both programs - "dual eligibles" or "duals," for short. The guide is also intended as a general introduction to Medicare and Medicaid benefits and attendant relationships for analysts who may be less familiar with one or both programs.