Research arguing the validity of the construct of the addictive personality has been criticized for methodology and because it has often been based on a narrow group of personality dimensions. To identify personality differences between drug addicts and college students from two different cultures, four groups of subjects, aged 17-25, were tested. The groups were representative of the following four areas: college students from New Orleans, college students from San Juan, drug addicts from New Orleans, and drug addicts from San Juan. Psychological differences were measured by the Eysenck Personality Inventory and the Adjective Check List. Demographic information was collected by the use of a locally constructed questionnaire. All instruments were administered in either an English or Spanish version. Separate 2X2 analyses of variance were used for each variable studied. Significant differences were identified between populations (drug addicts and college students) on seven variables; significant differences were identified between cities (New Orleans and San Juan) on eight variables. The finding of ten significant interactions between populations and cities makes it difficult to summarize these findings. It is clear, however, that cultural differences (differences between cities) are less common than are population differences or interactions between populations and cities. (Author)