THE SUITABILITY OF THE BLUE, GREEN, AND YELLOW VERSION BIOLOGICAL SCIENCES CURRICULUM STUDY (BSCS) FOR THE UPPER 75 PERCENT OF THE STUDENTS TAKING TENTH GRADE BIOLOGY IN THE UNITED STATES IS EXAMINED AND PROCEDURES USED IN ASSIGNING SLOW LEARNERS TO CLASSES USING BSCS SPECIAL MATERIALS ARE SURVEYED. THE SUITABILITY STUDY INVOLVED 12,602 STUDENTS AND THE SPECIAL MATERIALS PHASE INCLUDED 38 CLASSES IN DESIGNATED TEST SCHOOLS. STUDENTS IN THE SUITABILITY STUDY WERE PRETESTED AT THE BEGINNING OF THE YEAR FOR ABILITY TO USE THE PROCESSES OF SCIENCE AND FOR NUMERICAL AND VERBAL REASONING ABILITY. THEY WERE POST-TESTED AT THE END OF THE YEAR FOR UNDERSTANDING OF SCIENCE CONCEPTS AND FOR THEIR ABILITY TO USE BIOLOGICAL INFORMATION. MULTIPLE CORRELATIONS WERE USED TO ANALYZE FINDINGS. THE BLUE, YELLOW, AND GREEEN VERSIONS OF BSCS BIOLOGY APPEARED TO BE SUITABLE FOR USE WITH MOST STUDENTS AT OR ABOVE THE 50TH PERCENTILE AND A MAJORITY OF THE STUDENTS IN THE 40TH TO THE 50TH PERCENTILE IN GENERAL ABILITY AS DETERMINED BY THE DIFFERENTIAL APTITUDE TEST. BSCS BIOLOGY SPECIAL MATERIALS WERE PREPARED FOR STUDENTS OF LOWER ABILITY. DATA OBTAINED INDICATED AT LEAST 50 PER CENT OF THE SCHOOLS WERE NOT SYSTEMATICALLY USING SCORES FROM GENERAL ABILITY AND/OR READING ABILITY TESTS DETERMINING ASSIGNMENT OF STUDENTS TO SPECIAL MATERIALS CLASSES. THIS ARTICLE IS PUBLISHED IN THE "JOURNAL OF RESEARCH IN SCIENCE TEACHING," VOLUME 3, ISSUE 1, 1965. (AG)