A SAMPLE OF 15-YEAR-OLDS WAS LOCATED AND TESTED AS AN ESSENTIAL PART OF PROJECT TALENT, A NATIONAL INVENTORY OF APTITUDES AND ABILITIES OF HIGH SCHOOL YOUTH. A PROBABILITY SAMPLE OF ALL 15-YEAR-OLDS IN THE UNITED STATES WAS ESTABLISHED, CONSISTING OF 4 1/2 PERCENT OF ALL SUBJECTS IN GRADES 9 THROUGH 12 AND LESS THAN ONE-HALF OF ONE PERCENT OF ALL OTHERS. THE 9 THROUGH 12 GRADE SEGMENT WAS TESTED AS PART OF THE PROJECT TALENT TESTING. THE PROJECT TALENT BATTERY OF TESTS INCLUDED A NUMBER OF APTITUDE AND ACHIEVEMENT MEASURES. A SPECIAL QUESTIONNAIRE WAS USED FOR INFORMATION ON LAST GRADE COMPLETED, REASON FOR DROPPING OUT, AND OTHER FACTS. DATA WERE ANALYZED FOR THE SAMPLE OF 15-YEAR-OLDS, THOSE NOT ATTENDING SCHOOL, AND PROJECT TALENT. RESULTS WERE DISCUSSED IN NINE CATEGORIES. AN IMPORTANT OUTCOME WAS THE DEVELOPMENT OF NATIONAL NORMS ON A VARIETY OF APTITUDE AND ACHIEVEMENT VARIABLES, BASED ON 75,000 SUBJECTS, REPRESENTING A COMPLETE AGE GROUP. (RS)