Review of permits for land disposal of hazardous wastes requires numerous decisions concerning policy and technical issues. Some require interpretation and application of information in research reports, other involve interpretation and evaluation of specialized test data, and others involve assessment of compliance with latest regulatory policies. Specialized knowledge concerning a number of technical areas and a broad base of environmental regulatory experience are necessary to adequately perform these reviews. The need for current knowledge and background, in addition to the concern that reviews be consistent prompted the authors int systems derest in expert systems. The paper presents the history, current status, and future direction of the expert evelopment program supported by the Waste Minimization, Destruction and Disposal Research Division of the Risk Reduction Engineering Laboratory. The development methods being used and some of the authors' experiences are also presented.