THE "CASE" PROGRAM WAS DEVELOPED TO PROVIDE A VEHICLE FOR UNDERSTANDING THE PSYCHOLOGICAL PROCESSES INVOLVED IN CONCEPT LEARNING BY MEANS OF COMPUTER SIMULATION TECHNIQUES. BECAUSE THE MAJORITY OF PUBLISHED "SIMULATION OF CONCEPT LEARNING" PROGRAMS PROVIDED FEW INSIGHTS INTO THE LEARNING PROCESS, THE "CASE" PROGRAM WAS DESIGNED TO PROVIDE A BETTER MEANS FOR OBTAINING SUCH INSIGHTS. A PSEUDOCODE SCHEME WAS USED WITH A SPECIAL INTERPRETER WRITTEN IN MACHINE LANGUAGE WHICH PERMITTED SUBROUTINES TO BE USED IN SEVERAL CONTEXTS WITHOUT HAND CODING THE SITUATIONALLY DEPENDENT LINKAGES. A THREE-LEVEL MODEL OF HUMAN MEMORY INVOLVING WORKING MEMORY, SHORT-TERM MEMORY, AND LONG-TERM MEMORY WAS USED TO PROVIDE A FLEXIBLE MEANS FOR ACQUIRING, PROCESSING, AND STORING INFORMATION. "CASE" THUS REPRESENTS A SMALL PROGRAMING SYSTEM RATHER THAN A SPECIFIC COMPUTER PROGRAM AND, AS SUCH, CONTINUALLY CHANGES AS IMPROVED UNDERSTANDINGS ARE OBTAINED. AT THE TIME OF REPORTING, THE "CASE" COMPUTER PROGRAM WAS PRIMARILY A MEDIUM FOR EXPRESSING AND STORING THE INSIGHTS AND UNDERSTANDINGS OF THE CONCEPT LEARNING PROCESS WHICH HAVE BEEN ACQUIRED. THIS PAPER WAS PREPARED FOR PRESENTATION AT THE FALL JOINT COMPUTER CONFERENCE (LAS VEGAS, NOVEMBER 30 - DECEMBER 2, 1965). VARIOUS ASPECTS OF THE DEVELOPMENT OF THE PROGRAM ARE PRESENTED IN THREE PAPERS APPENDED TO THIS DESCRIPTION OF CASE. THESE PAPERS COVER (1) "CONCEPT ATTAINMENT EXPERIMENTATION BY COMPUTER SIMULATION," (2) " EXPERIMENTAL DESIGN CONSIDERATIONS ASSOCIATED WITH LARGE SCALE RESEARCH PROJECTS," AND (3) "AN IPL-V TECHNIQUE FOR SIMULATION PROGRAMS." (JH)