INTERVIEWERS VISITED SELECTED HOUSEHOLDS IN ORDER TO LIST RESIDENTS FOR PURPOSES OF RANDOM SELECTION. THE INDIVIDUALS IN EACH HOUSEHOLD WERE LISTED BY AGE GROUP, SO THAT YOUTH (12 TO 17 YEARS), YOUNG ADULTS (18 TO 25 YEARS), AND OLDER ADULTS (26 YEARS OR OLDER) COULD BE SAMPLED SEPARATELY. THE OVERALL RESPONSE RATE FOR THE NATIONAL SURVEY WAS 80 PERCENT. YOUNG ADULTS REPORT THE HIGHEST USE OF ALL DRUGS STUDIED, EXCEPT ALCOHOL. MARIJUANA IS THE MOST COMMONLY USED DRUG, OTHER THAN ALCOHOL, WITH ONE-FOURTH OF YOUNG ADULTS, ONE-SIXTH OF YOUTH, AND 1 OUT OF 30 OLDER ADULTS REPORTING CURRENT USE. USE OF COCAINE AND HALLUCINOGENS FOR ALL AGES IS LOW, BUT 4 TO 5 PERCENT OF YOUTH, 20 PERCENT OF YOUNG ADULTS, AND 3 TO 4 PERCENT OF OLDER ADULTS REPORT SOME USE. LESS THAN 0.5 PERCENT OF ANY AGE GROUP REPORTS CURRENT USE OF HEROIN, ALTHOUGH STATISTICS MAY BE MISLEADING. ABOUT 13 TO 21 PERCENT OF YOUNG ADULTS REPORT NONMEDICAL EXPERIENCE WITH SEDATIVES AND STIMULANTS, WHICH IS SUBSTANTIALLY LESS AMONG OTHER GROUPS. CURRENT USE OF ALCOHOL IS REPORTED 58 PERCENT OF ALL ADULTS AND 31 PERCENT OF YOUTH. OVERALL, SOME USE OF A DRUG STRONGER THAN MARIJUANA OR HASHISH IS REPORTED BY ONE-FOURTH OF YOUNG ADULTS, ONE TWENTY-FIFTH OF OLDER ADULTS, AND ONE-TENTH OF YOUTH. ADDITIONAL FINDINGS OF THE STUDY ARE DETAILED, AND MANY TABLES AND FIGURES ARE PRESENTED. APPENDIXES INCLUDE REPORTS ON DATA QUALITY, SAMPLING AND WEIGHING METHODS EMPLOYED; AND EXAMPLES OF THE QUESTIONNAIRES. (PAP)