These proceedings, from a conference held at the Federal Reserve Bank of St. Louis on October 17-18, 1991, attempted to layout what we currently know about aggregate economic fluctuations. Identifying what we know inevitably reveals what we do not know about such fluctuations as well. From the vantage point of where the conference's participants view our current understanding to be, these proceedings can be seen as suggesting an agenda for further research. The conference was divided into five sections. It began with the formu lation of an empirical definition of the "business cycle" and a...