IT IS POINTED OUT THAT THE FIRST RULE OF DATA DISPLAY IS TO KNOW THE PURPOSE OF THE DISPLAY. THAT PURPOSE CAN BE COMMUNICATION (KNOWING SOMETHING AND WANTING TO TELL OTHERS ABOUT IT); EXPLORATION (USING GRAPHIC DISPLAYS TO ANALYZE DATA); RECONSTITUTION (USING THE DISPLAY TO HELP THE USER RECONSTITUTE THE DATA FROM WHICH IT WAS BUILT); OR DECORATION. EACH PURPOSE IS DISCUSSED, AND EXAMPLES OF GRAPHICS AND TABULAR PRESENTATIONS SERVING EACH PURPOSE ARE PRESENTED. A BRIEF HISTORY OF GRAPHICS IS FOLLOWED BY GUIDELINES FOR EFFECTIVE USE OF GRAPHICS. EXAMPLES OF GRAPHIC DISPLAYS ILLUSTRATE THE GUIDELINES, WHICH ARE THEN APPLIED TO THE DEVELOPMENT OF GRAPHIC DISPLAYS FROM TABULAR DATA ON CASE DISPOSITION IN JUVENILE COURTS. A LIST OF REFERENCES IS INCLUDED. (LKM)