FORMAL SANCTIONS INCLUDED PERCEIVED CERTAINTY OF APPREHENSION AND PERCEIVED SEVERITY OF AVAILABLE PUNISHMENTS; INFORMAL ITEMS PERTAINED TO PERCEIVED FAMILY ATTITUDES TOWARD MARIHUANA USE. ANALYSIS OF DATA INDICATED A STRONG, INVERSE RELATIONSHIP BETWEEN PERCEIVED CERTAINTY OF PUNISHMENT AND ADMITTED USE, WITH THE PROPORTION OF MARIJUANA USERS BEING SEVEN TIMES GREATER AMONG SUBJECTS WHO PERCEIVED LITTLE LIKELIHOOD OF APPREHENSION. HOWEVER, THE PERCEIVED SEVERITY OF PUNISHMENT IS ONLY SLIGHTLY RELATED TO ADMITTED USE. MARIHUANA USE IS ALSO STRONGLY RELATED TO PEER AND FAMILY APPROVAL: THE PROPORTION OF MARIHUANA USERS AMONG THOSE PERCEIVING PEER APPROVAL IS SIX TIMES GREATER THAN AMONG THOSE PERCEIVING DISAPPROVAL, AND THE DIFFERENCE IN USE BETWEEN THOSE PERCEIVING FAMILY APPROVAL AND THOSE PERCEIVING STRONG FAMILY DISAPPROVAL IS ALMOST AS GREAT. FINALLY, THE PROPORTION OF MARIHUANA USERS IS TEN TIMES GREATER AMONG THOSE WHO REPORT THREE TO FIVE USING PEERS THAN AMONG THOSE REPORTING NO USING PEERS. WHILE THESE CORRELATIONS WERE SLIGHTLY STRONGER FOR MALES THAN FOR FEMALES, THE DIFERENCE BY SEX WAS NOT SIGNIFICANT. FURTHER ANALYSIS INDICATES THAT, ALTHOUGH PERCEIVED SEVERITY OF FORMAL PUNISHMENT IS UNRELATED TO REPORTED MARIHUANA USE, THE DETERRENT EFFECTIVENESS OF PERCEIVED SEVERITY IS SUBSTANTIALLY INCREASED FOR SUBJECTS PERCEIVING A HIGH CERTAINTY OF PUNISHMENT. THE RELATIVE DETERRENT IMPACT OF PERCEIVED INFORMAL SANCTIONS IS GREATER THAN THE IMPACT OF PERCEIVED CERTAINTY OF PUNISHMENT, AND THE CUMULATIVE IMPACT OF PERCEIVED CERTAINTY AND PERCEIVED INFORMAL SANCTIONS IS GREATER THAN THE IMPACT OF EITHER ALONE. REFERENCES ARE PROVIDED. (JAP)