Two samples of participants from the U.S.–Mexico Borderland (N = 185) versus Spain (N = 205) were compared on 16 Spanish-language neuropsychological measures. In most measures the two samples obtained similar results. There were some significant main effects of place of birth and some significant interactions between education and place of birth. Differences between the samples diminished with increasing levels of education. Within the Borderland sample, percent of life span spent in the U.S. and bilingual status were correlated with performance in some tests. Increased percent of life span spent in the U.S. was negatively correlated with performance on a Spanish word-generation task, and positively correlated with performance on the Wisconsin Card Sorting Test. Bilingual Borderland participants performed significantly better than monolingual speakers in learning a list of words. We suggest that the most likely causes for the observed interaction effects are documented regional differences in early SES-related nutrition, medical care, quality of educational experiences, and general socioeconomic conditions. (JINS, 1998, 4, 363–379.)