THIS STUDY INVESTIGATES THE POTENTIALLY FACILITATIVE AND INHIBITORY EFFECTS OF SOCIAL INTERACTION DURING PROGRAMED INSTRUCTION. SPECIFIC OBJECTIVES WERE (1) TO IDENTIFY THE PARTICULAR ASPECTS OF SOCIAL INTERACTION CRITICAL TO FACILITATING OR INHIBITING PROGRAMED LEARNING, AND (2) TO DETERMINE THE METHOD OF CONSTRUCTING WORK GROUPS THAT OPTIMIZES LEARNING FOR BOTH LOW AND HIGH ABILITY STUDENTS. ONE HUNDRED AND EIGHTY ELEVENTH-GRADE STUDENTS COMPLETED A 660-FRAME LINEAR PROGRAM, WORKING EITHER INDIVIDUALLY OR IN A GROUP OF FOUR CLASSMATES HOMOGENEOUS OR HETEROGENEOUS IN ABILITY. GROUPS OF EACH TYPE WORKED UNDER ONE OF THREE CONDITIONS THAT PROVIDED FOR INCREASING DEGREES OF SOCIAL INTERACTION--(1) GROUP PACING, (2) GROUP PACING AND PUBLIC KNOWLEDGE OF RESULTS, AND (3) GROUP PACING, PUBLIC KNOWLEDGE OF RESULTS, AND GROUP DISCUSSION. DEPENDENT MEASURES INCLUDED ERROR RATE, COMPLETION TIME, IMMEDIATE AND DELAYED CRITERION-TEST SCORES, AND STUDENT ATTITUDE TOWARD THE CONTENT AND METHOD OF INSTRUCTION. THE ONLY OBSERVED DIFFERENTIAL EFFECT OF SOCIAL INTERACTION WAS IN PROGRAM COMPLETION TIME WHICH TENDED TO INCREASE AS THE DEGREE OF INTERACTION INCREASED. LEARNING EFFICIENCY WAS GREATEST FOR STUDENTS WHO WORKED AS INDIVIDUALS. HOMOGENEOUS AND HETEROGENEOUS GROUPS DID NOT DIFFER FROM EACH OTHER ON ANY DEPENDENT MEASURE. THUS, THE ADMINISTRATION OF PROGRAMS TO INTERACTING GROUPS IMPEDED LEARNING EFFICIENCY WITHOUT AFFECTING ACHIEVEMENT OR ATTITUDE. (HM)