The purpose of this study was to examine the Thai Emotional Intelligence Screening Test (TEIST), which has been used extensively as a research and survey tool in Thailand since 2000. However, only a limited number of studies has examined the psychometric properties of the TEIST. Claims concerning test reliability, factor structure, and validity are yet to be substantiated. This study employed a mixed-methods research design to investigate the psychometric values of the TEIST, and was conducted over two phases. The first phase investigated the reliability and validity of the TEIST. The second phase of the study validated the revised version of the TEIST. Further validation of the TEIST to assess emotional intelligence was examined by comparing the TEIST to the Wong and Law Emotional Intelligence Scale (WLEIS), a well-validated measure of emotional intelligence. The quantitative results from the first phase of the study showed that the internal reliability of this original 52-item TEIST was equivalent to the reliability earlier reported by the Ministry of Public Health (2000). Confirmatory factor analysis via structural equation modelling indicated that the factors were consistent with the underlying theories of the measure examined; even though the 52-item TEIST was not found to provide an acceptable fit to the data according to the standard model fit statistics. The revised 15-item TEIST provided a statistically significant fit with the present data. Quantitative analysis revealed the psychometric properties of the revised version of the TEIST. Multivariate analysis of variance (MANOVA) was used to assess the effects of order, cultural group, gender, and response-scale format. The analysis indicated that gender and group had positively significant effects on outcome scores at the multivariate level. Qualitative analysis using Leximancer was used to better understand what components and what themes might have been inherent in the text of the items of the TEIST, the WLEIS, and the responses to the interview. The qualitative findings indicated that concepts inherent in the TEIST were associated with the ability to manage one’s own and others’ emotions. In addition, the TEIST was able to distinguish between two groups of participants by indicating contrasting aspects of coping strategies. Qualitative results from the second phase of the study indicated that concepts inherent in the WLEIS items were related to the ability to understand and regulate one’s own and others’ emotion. Overall, the results from both quantitative and qualitative frameworks offered some evidence for the reliability and validity of the TEIST; however, further development and evaluation of the shortened version of the TEIST is warranted. This study complements the body of psychometric knowledge of the TEIST, introduces a shortened instrument with increased reliability and construct validity, and provides new theoretical and measurement insight into emotional intelligence across culture and within specific cultural settings. Specifically, it challenges the claim that emotional intelligence varies across cultural groups.