Subjects were classified into one of five pattern-of-use groups based on marijuana usage: principled nonusers, nonusers, light users, moderate users, and heavy users. Principled nonusers (individuals who have never used marijuana and would not do so if it was legalized) rated marijuana, hashish, cocaine, and alcohol as significantly more harmful than heavy users. A cluster analysis of the drugs' harmfulness ratings best fit a three- cluster solution and were named medicinal drugs, recreational drugs, and hard drugs. Generally, principled nonusers rated negative consequences from using marijuana as significantly more likely to occur than other groups. Principled nonusers and heavy users utilized reversal from the Defense Mechanism Inventory, which includes repression and denial, significantly more than nonusers, indicating some traits common to the two extreme pattern-of-use groups. 4 tables and 17 references