In this review, the authors propose that the fear extinction model can be used as an experimental tool to cut across symptom dimensions of multiple anxiety disorders to enhance our understanding of the psychopathology of these disorders and potentially facilitate the detection of biomarkers for them. The authors evaluate evidence for this proposition from studies examining the neurocircuitry underlying fear extinction in rodents, healthy humans, and clinical populations. The authors also assess the potential use of the fear extinction model to predict vulnerability for anxiety and treatment response and to improve existing treatments or develop novel ones. Finally, the authors suggest potential directions for future research that will help to further validate extinction as a biomarker for anxiety across diagnostic categories and to bridge the gap between basic neuroscience and clinical practice.