Excessive reassurance seeking (ERS) is believed to play an important role in maintaining mental health problems, in particular anxiety disorders such as obsessive-compulsive disorder and health anxiety. Despite this, therapists commonly give into patients' requests for reassurance in clinical settings and are generally unsure how to handle the issue both in therapy itself and concerning advice to the patient's loved ones. In order to increase our understanding of therapists' perception of ERS and how interventions for ERS are managed, we examined therapists' perception and understanding of ERS, including its function, which emotional problems therapists associate it with, and what treatment interventions they consider important for managing ERS. Qualified therapists (n=197) were benchmarked against international expert consensus (n=20) drawn from leading clinical researchers. There was evidence that clinical experience right up to the expert level may result in less reassurance giving within treatment settings. Still, there were enough inconsistencies between the experts and other clinicians to suggest that ERS remains poorly understood and is not consistently dealt with clinically. Results are discussed in terms of how current treatment interventions may be limited for treating ERS, highlighting the need to consider new approaches for dealing with this complicated interpersonal behaviour. Key learning aims (1) To describe the role of excessive reassurance seeking in checking behaviour, including its negative personal and interpersonal consequences. (2) To learn that therapists commonly report finding it difficult to manage reassurance seeking. (3) To learn that therapists' beliefs about excessive reassurance seeking may play a key role in helping us understand how to tackle this complicated behaviour. (4) To consider what therapeutic interventions may be appropriate and helpful for treating excessive reassurance seeking.