Objectives There are a number of effective psychological interventions for anxiety disorders. Anecdotal and empirical evidence indicates that clients are often highly apprehensive about commencing therapy. However, to date, there have been no empirical studies of the content of individuals’ fears about beginning a psychological treatment for anxiety problems. Here we describe the development and initial validation of the Treatment Ambivalence Questionnaire (TAQ), a 30‐item self‐report measure of concerns about commencing psychological treatment for anxiety. Methods Participants were a large group of individuals with a principal diagnosis of an anxiety disorder who were referred to a specialty anxiety disorders clinic. Participants completed the TAQ as well as several general self‐report instruments before commencing treatment. Results The TAQ exhibited good internal consistency and, based on exploratory factor analyses, the items yielded three subscales: (a) fears of the personal consequences of engaging in treatment (e.g., personality change), (b) fears of negative or adverse reactions to treatment (e.g., not getting better), and (c) concerns about the inconvenience of engaging in treatment (e.g., treatment will be time‐consuming). Confirmatory factor analysis supported this factor structure. Scores on the TAQ did not simply represent general symptom severity or distress. Preliminary data on the relation of TAQ scores to treatment outcome suggested either no relationship or a small relationship. Conclusion The TAQ may be a useful means of normalizing treatment fears, identifying and addressing specific fears, and identifying people who may benefit from treatment readiness interventions.