VARIOUS WAYS WERE EXPLORED BY WHICH PRIOR OR PREREQUISITE LEARNING AFFECTS THE LEARNING OF HIGHER ORDER (CRITERION) MATERIAL WHICH BUILDS ON PREVIOUS EDUCATIONAL FOUNDATIONS. THE INVESTIGATION WAS CONCERNED WITH THREE INSTRUCTIONAL VARIABLES (PACING, PRACTICE, AND NUMBER OF STAGES IN A LEARNING HIERARCHY) AND THEIR EFFECTS ON LEARNING RETENTION AND TRANSFER OF PROBLEM-SOLVING SKILLS. IN ADDITION, RELATIONSHIPS BETWEEN THESE INPUT VARIABLES WERE EXPLORED. EXPERIMENTS USED IN THE PROJECT WERE ENTITLED AS FOLLOWS--(1) "PROBLEM SOLVING AND PRIOR LEARNING," (2) "ALGORITHM LEARNING AND PROBLEM SOLVING," (3) "PRIOR LEARNING, PRESENTATION ORDER, AND PREREQUISITE PRACTICE IN PROBLEM SOLVING," AND (4) "PREREQUISITE PRACTICE AND CRITERION FORM IN MATHEMATICS LEARNING." THESE EXPERIMENTS WERE RUN ON GROUPS OF 15 TO 40 COLLEGE STUDENTS. THESE SUBJECTS WERE TESTED ON CRITERION, GENERALIZATION, AND NONSPECIFIC TRANSFER TASKS IMMEDIATELY AFTER LEARNING AND, AGAIN, AFTER 5 WEEKS (USING PRACTICE WITH SUBORDINATE MATERIAL AND CRITERION PRACTICE). STANDARD ANALYSIS VARIANCE PROCEDURES PROVIDED THE BASIS FOR MOST OF THE INFERENCES. LEARNING ABILITY WAS FOUND TO BE FAR FROM INNATE. IT DEPENDED FUNDAMENTALLY ON THE AMOUNT OF PREREQUISITE LEARNING ALREADY AVAILABLE. THE NEED FOR FURTHER RESEARCH IN THE FIELD OF INDIVIDUALIZED INSTRUCTION IS STRESSED. (JH)