Personality differences among black populations of varying socioeconomic background from Jamaica and the United States were investigated using Rotter's Internal-External Locus of Control measure, Gough's Adjective Check List, and Kelly's Role Construct Repertory Test. Results demonstrate the differential utility of these personality measures for cultural comparisons, and in particular suggest that the I-E Scale lacks equivalence of meaning cross-culturally as well as for differing sample populations within the United States. Differences in personality traits and social constructs were generally consistent with those that might be predicted between members of a more traditional society and those of a modern nation. The view that studies of racial minorities within a nationality are appropriately conducted in a cross-cultural framework is presented.