This report is the summary of a workshop held by The Institute of Medicine (IOM) of the National Academy of Science December 13-14, 2004 to estimate the contributions of lifestyle-related factors to preventable death. The summary of this workshop includes presentations from experts in statistical design, epidemiology, quality-of-life measures, communication, and public policy and discussions among the participants. Panels of experts addressed the following topics: methodological issues when estimating the public health burden of lifestyle factors; estimating "attributable risk" in practice; alternative ways of measuring the health burden; and public policy issues.