A knowledge of forest site and forest productivity variables is fundamental to sound forest practice everywhere. The ability to identify sites and site problems correctly and manipulate productivity variables for maintenance or improvement of productivity is the basis of modern forest management. Although the basic facts regarding forest site and productivity apply throughout the world, the application of information and the response to manipulation vary greatly and depend on local forest conditions. The September 1981 World Congress of the International Union of Forest Research Organizations (IUFRO) in Kyoto, Japan was the occasion for the special meeting on Forest Site and Productivity sponsored by the IUFRO Site Group Sl.02. This meeting brought together forest site and productivity researchers from across the world to review current thought and the state of site research. Information not ordinarily available in one place was presented at this meeting. As organizer of the session, I decided to attempt to publish the papers in one volume. Arrangements were made with a publisher, Martinus Nijhoff, and also with the authors. The process of publication has taken longer than desirable, but the volume does appear at an opportune time coincident with the 1986 IUFRO World Congress in Yugoslavia. Material contained in this publication will set the stage for Site Group discussions at the 1986 meeting. This volume assembles the thought of forest research workers from many different countries and therefore many different kinds of forests.