Search Theory and Unemployment contains nine chapters that survey and extend the theory of job search and its application to the problem of unemployment. The volume ranges from surveys of job search theory that take microeconomic and macroeconomic perspectives to original theoretical contributions which focus on the externalities arising from non-sequential search and search under imperfect information. It includes a clear and authoritative survey of econometric methods that have been developed to estimate models of job search, as well as two lucid contributions to the empirical search literature. Finally, it includes a study that reviews and extends the literature on optimal unemployment insurance and concludes with an appraisal of the influence of search theory on the thinking of macroeconomic policymakers.