Background: The importance of post-event processing (PEP) in prominent models of social anxiety disorder has led to the development of measures that tap this cognitive construct. The 17-item Extended Post-event Processing Questionnaire (E-PEPQ) is one of the most comprehensive measures of PEP developed to date. However, the measure was developed in German and the psychometric properties of the English version of the E-PEPQ have not yet been examined. Design: The current study examined the factor structure, internal consistency, and construct validity of the English version of the E-PEPQ. Methods: English-speaking participants (N = 560) completed the English version of the E-PEPQ, a measure of social anxiety and a measure of depression. Results: A 15-item version of the E-PEPQ with a correlated three-factor structure (referred to as the E-PEPQ-15) emerged as the best fitting model using confirmatory factor analyses, and the E-PEPQ-15 and its subscales demonstrated good internal consistency. The E-PEPQ-15 and two of its three subscales also had significantly stronger positive associations with the social anxiety measure than with the depression measure. Conclusions: The psychometric properties of the E-PEPQ-15 obtained in the current study justify the use of the measure in research, particularly in the domain of social anxiety.