The Reinsurance Institute provided quantitative modeling and qualitative analysis to states as they explored reinsurance as an element of health reform. The project estimated the impacts of reinsurance, including changes in premiums, employer offer and enrollee take-up of coverage, numbers of people insured, and costs to the state. Small numbers of high spenders account for a large share of health spending, but most spending occurs in lower corridors of expense. Medical spending varies widely by age and health status, creating pressure for risk segmentation. Lastly, defining the eligible population determined whether reinsurance would cover new enrollees or solidify current coverage.