Fear and anxiety are common and often transient human responses to stressors, danger, or traumatic events. However, when fear and anxiety persist over time, and result in functional impairment, an anxiety disorder may be present. In both the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5) (APA, 2013) and the ICD-11 (World Health Organization, 2018) the category of ‘anxiety disorders’ includes a range of conditions that share characteristics of excessive fear or anxiety with consequent distress and impairment. These include generalized anxiety disorder, panic disorder, agoraphobia, and social anxiety disorder (social phobia), among others. This chapter focuses on these conditions with particular reference to how they affect adult men. In addition, obsessive-compulsive disorder (OCD), an anxiety-related disorder placed in a separate DSM-5 and ICD-11 category called ‘Obsessive-Compulsive and Related Disorders’, is also included here due to its historical positioning as an anxiety disorder in earlier editions of the DSM and ICD. Posttraumatic stress disorder (PTSD) has also been reclassified in DSM-5 and ICD-11 from an anxiety disorder to a new diagnostic category known as ‘Trauma and Stressor-Related Disorders’, and is discussed in Chapter 10.