The popular conception of illegal drug use as inevitably pushing users toward compulsive drug abuse, and the ideological stance that drug use is a moral weakness, are offered by many as justification for punitive drug control. Challenging this view are the research on "set and setting" as determinants of the consequences of drug use, and the harm reduction movement that aims to ameliorate the potentially negative impact of drug use. One implication of these alternative approaches is that adults may be at increased risk for developing harmful patterns of drug use if their conceptualizations of the nature of illegal drug use exclude the possibility of controlled use as one possible pattern. The present study was designed to address these possibilities by investigating the relationship between how adults think about illegal drug use and their patterns of drug use. The hypotheses tested were that adults who possess a dichotomous conceptualization of the nature of illegal drug use and those who express less acceptance for using guidelines for drug use are at increased risk of developing harmful patterns of drug use. Results and recommendations for future research are discussed. Appended are tables with study's results. (JDM)