THE SAMPLE WAS COMPOSED OF 1,413 STUDENTS. STUDENTS WERE EXPOSED TO 2 YEARS OF DRUG EDUCATION ACCORDING TO THE FOLLOWING MODES: CONTROL GROUP, A STATE-REQUIRED SUBJECT WITH NO SPECIFIED NUMBER OF HOURS PER YEAR; DIDACTIC GROUP, USING THE SAME CURRICULUM APPLIED IN A PREVIOUS DRUG EDUCATION EXPERIMENT; PROCESS GROUP, USING A GUIDED DISCUSSION FORMAT; COMBINED CURRICULUM GROUP, AN AMALGAM EMPLOYING BOTH DIDACTIC AND DISCUSSION FEATURES; AND A PARENT-INVOLVED GROUP. EACH STUDENT WAS CHARACTERIZED IN RELATION TO ONE OF NINE PATTERNS (ABSTAINER, LOW FREQUENCY USE OF CULTURALLY SANCTIONED SUBSTANCES, HIGH FREQUENCY USE OF SANCTIONED SUBSTANCES, LOW MARIHUANA USE, HIGH MARIHUANA USE, LOW AMPHETAMINE/BARBITURATE/ HALLUCINOGEN USE, HIGH AMPHETAMINE/BARBITURATE/ HALLUCINOGEN USE, LOW HEROIN/COCAINE USE, AND HIGH HEROIN/COCAINE USE). DRUG EDUCATION HAD AN IMPACT ON STUDENT NONMEDICAL PSYCHOACTIVE DRUG USE. THIS IMPACT VARIED; IT WAS STABILIZING, STIMULATING, RESTRAINING, AND REDUCING. IMPACT WAS RELATED TO THE MODE OF DRUG EDUCATION AND TO OUTCOME CRITERIA. THE MODALITY-DEPENDENT EFFECT WAS, IN TURN, A FUNCTION OF THE LEVEL OF DRUG USE BY STUDENTS WHEN THE DRUG EDUCATION EFFORT BEGAN. IMPACT ALSO VARIED WITH TEACHER CHARACTERISTICS BUT RARELY WITH SCHOOL. FORMAL DRUG EDUCATION FOR LOW-RISK POPULATIONS IS NOT RECOMMENDED, ALTHOUGH PARENTAL INVOLVEMENT IN FAMILY LIFE THAT TRANSMITS VALUES AND CONTROLS IS ADVOCATED TO REDUCE DRUG RISKS. SUPPORTING DATA AND REFERENCES ARE INCLUDED. (DEP)