Direct coal liquefaction, a synthetic liquid fuel process, is one of the major developmental alternatives for meeting the anticipated fuel demands for the twenty-first century. This work provides a retrospective assessment of past attempts in this century to develop synthetic liquid fuel and applies the findings to produce reliable and pertinent data for the future. Retrospective technology assessment, a recent methodological invention, is used by the authors to analyze the past synthetic liquid fuel programs and the reasons for their failures. Bringing to bear four different perspectives--economic, technological, policy, and historical--the authors draw broad conclusions that will help guide the next development effort in the United States.