Drug use is apparently less problematic from a sociological perspective; many drug users just "grow out of it," or use drugs in a controlled way; however, relapse rates are higher, and controlled use is less likely among clinical populations. Despite the greater heterogeneity of community samples, motivational or protective factors (e.g., avoidance of certain situations) appear similar to clinically based research. Cessation is linked to negative consequences of drug use. Participation in drug-use settings (e.g., social pressure from drug users) and intrusive thoughts (e.g., cravings for drugs) about drugs emerge as the greatest cause of relapse. Emergent themes of avoidance and intrusion indicate that research on post-traumatic stress could provide an interesting avenue for future clinical approaches. The phenomena of intrusion, avoidance, and cue reactivity, coupled with more general symptoms of negative affect and anxiety, generate interesting clinical parallels with the key symptoms experience by sufferers of post-traumatic stress disorder. Perhaps some of the cognitive elements of post-traumatic stress disorder treatment may be used to augment and overcome the limitations of purely behavioral approaches to drug use. 63 references