Abstract: Introduction: The Lehrer–Woolfolk Anxiety Symptom Questionnaire (LWASQ) is a self-report questionnaire based on the tripartite model of Lang (1971) for measuring treatment progress. However, so far little is known about its psychometric qualities. Two studies were conducted to get more clarity on the factor structure and reliability of the LWASQ. Method: Factor structure and internal consistency of the LWASQ were assessed using a sample of 2,117 patients with anxiety disorders. Test–retest reliability was measured with a three-week interval, using a sample of 49 people in a general population. We aimed to measure construct validity with a third sample of patients with anxiety disorders, but were not able to due to a small sample size. Results: Factor analysis confirmed the three known factors of the LWASQ, i.e., somatic complaints, cognitive problems, and behavioral complaints. Both internal consistency for all three subscales (r = .852–.927) and test–retest reliability were found to be good (r = .88). Conclusion: Psychometric properties of the LWASQ are promising, but further validation is needed to draw more definitive conclusions regarding its usefulness in a clinical population.