The goals of the study were to examine whether fundamentalism and authoritarianism could be distinguished by the Big Five factors of personality in American, Romanian and German samples, and to determine whether fundamentalism and authoritarianism could be distinguished by factor analysis in any of the three cultures. The results in all three cultures indicate that fundamentalism and authoritarianism have virtually identical personality correlates. In all three cultures, the two constructs were indistinguishable via exploratory factor analysis and could only be distinguished via confirmatory factor analysis, although direction-of-wording effects dwarfed the differences between fundamentalism and authoritarianism. The findings suggest that researchers should view fundamentalism as religious authoritarianism, and should therefore be cautious when making inferences about religiosity from research on fundamentalism.