THE EFFECTS OF INSTRUCTIONS, TYPE OF LABEL, TYPE OF CONCEPT, AND SEQUENCE OF CONCEPTS BY TYPE UPON CONCEPT IDENTIFICATION WERE INVESTIGATED IN THIS STUDY. PERFORMANCE WAS ANALYZED IN TERMS OF FOUR TYPES OF TEST ITEMS. INSTRUCTION, FOCUSING ON THE CONCEPT TO BE ATTAINED AND THE CONCEPT NATURE, WAS FOUND TO FACILITATE CONCEPT IDENTIFICATION SIGNIFICANTLY BETTER THAN INSTRUCTION DESIGNED ONLY TO ACQUAINT STUDENTS WITH STIMULUS MATERIALS. STUDENTS PERFORMED AS WELL ON A SEQUENCE IN WHICH THEY IDENTIFIED TWO CONJUNCTIVE CONCEPTS FOLLOWED BY DISJUNCTIVE CONCEPTS AS THEY DID ON A SEQUENCE OF TWO DISJUNCTION CONCEPTS FOLLOWED BY TWO CONJUNCTIVE CONCEPTS. PRIOR EXPERIENCE WITH EITHER CONJUNCTIVE OR DISJUNCTIVE CONCEPTS TENDED TO LOWER LATER PERFORMANCE ON THE OTHER TYPE OF CONCEPT. USE OF LABELS OF HIGH FREQUENCY OCCURRENCE DID NOT RESULT IN PERFORMANCE SIGNIFICANTLY DIFFERENT FROM THAT OF LABELS OF LOW FREQUENCY OCCURRENCE. EXAMPLES OF THE CONCEPT CONTAINING NEITHER OR BOTH RELEVANT ATTRIBUTES WERE EASIER FOR SUBJECTS TO CLASSIFY AS BELONGING OR NOT BELONGING TO THE CONCEPT THAN EXAMPLES WITH ONLY ONE OR THE OTHER RELEVANT ATTRIBUTE PRESENT. (JC)