In this study 413 English males and females completed the Cloninger Tridimensional Personality Questionnaire (TPQ). Internal consistency, factor structure, and construct validity were investigated, and comparisons made between the TPQ scores of the English sample and Cloninger's U.S. normative data. Doubts were raised about the reliability of some of the 12 subscales of the TPQ. The harm avoidance scale was found to be the most reliable, and the reward dependence scale the least reliable of the three higher-order personality scales. An exploratory factor analysis of the 12 subscales produced a three-factor solution for the females, similar to Cloninger's proposed model but a four-factor solution for the males. Confirmatory factor analyses indicated that there were some significant differences between Cloninger's proposed three-factor solution and the empirically derived solution. Further research is required to test and possibly adapt the current form of the TPQ to ensure its reliability for use within the English population.