Anxiety in later life is relatively common in older populations but remains under-diagnosed and treated. Both primary and comorbid anxiety disorders in later life contribute to overall burden of disease, which is reflected in excess morbidity and mortality. One important means to reduce excess burden and instigate appropriate treatments for older adults with anxiety is to accurately assess this condition more across diagnoses and settings. The introduction of the Geriatric Anxiety Inventory and its variations has made an impact on assessment of anxiety research internationally, contributing to the growing global interest in the topic of late-life anxiety. This article discusses reasons for developing the test, processes of test construction, description of the most recent versions of the test, issues in developing culturally-appropriate normative data, adoption of the tests by researchers and clinicians, and future development plans for the test.