New medical procedures and treatments can improve health outcomes, but they also are a major factor in the rapid rise of health care costs. What makes this trade-off particularly problematic is the lack of data on which procedures and treatments work and in which situations they are effective, as well as the lack of a mechanism for making appropriate decisions even when such information is available. This project will seek to: 1) analyze the evidence and the process used by the Medicare program to determine which new medical technologies it will pay for; and 2) explore alternative decision-making mechanisms, including those used by private insurers and other countries, that Medicare might consider. The analysis will draw from a database that includes information on treatment coverage decisions made from 1999 through mid-2007.