THE LITERATURE ON LANGUAGE ABILITY AND ITS RELATIONSHIP TO ACADEMIC SUCCESS INCREASINGLY VOICES ALARM THAT THE CULTURALLY DISADVANTAGED ARE SERIOUSLY DEFICIENT IN LANGUAGE ABILITY. INTERVENTION PROGRAMS CREATED TO CORRECT THIS PROBLEM ALL RECOGNIZE THE IMPORTANCE OF LANGUAGE TOOLS FOR INTELLECTUAL FUNCTIONING. ESSENTIAL TO SUCH PROGRAMS, AND FREQUENTLY ABSENT FROM THEM, ARE RELIABLE MEASUREMENT TECHNIQUES FOR EVALUATING THE INTERACTION OF THE PROGRAM WITH THE CHILD'S COGNITIVE PROCESSES. THE PRESCHOOL LANGUAGE PROJECT AT THE UNIVERSITY OF CALIFORNIA AT LOS ANGELES IS CONSTRUCTING AND USING NEW MEASURING DEVICES--FOR EXAMPLE, THE VISUAL DISCRIMINATION INVENTORY (VDI). THE VDI WAS ADMINISTERED TO 291 PRESCHOOL CHILDREN TO OBTAIN DATA ON THE VISUAL DISCRIMINATION ABILITY OF THE 199 NEGRO AND 92 CAUCASIAN CHILDREN. THE CHILDREN REPRESENTED TWO LEVELS OF ECONOMIC STATUS AND RANGED IN AGE FROM 3 TO ALMOST 6. ADMINISTRATION OF THE VDI INVOLVED PRESENTING THE CHILD WITH A MODEL FIGURE AND THREE CHOICE FIGURES FROM WHICH TO SELECT THE ONE THAT MATCHED THE MODEL. AGE AND RACE APPEAR TO BE RELATED TO DISCRIMINATION ABILITY. THE VDI WAS FOUND TO HAVE BOTH RELIABILITY AND VALIDITY. THIS DOCUMENT IS COMPOSED OF TWO REPORTS. ONE WAS PRESENTED AT THE BIENNIAL MEETING OF THE SOCIETY FOR RESEARCH IN CHILD DEVELOPMENT (NEW YORK, APRIL, 1967) AND THE OTHER, AT THE AMERICAN PSYCHOLOGICAL ASSOCIATION ANNUAL MEETING (WASHINGTON, SEPTEMBER, 1967). (WD)