Our understanding of the neurobiological basis of fear and anxiety continues to improve at a rapid pace. The principal brain regions involved in processing and responding to anxiety are known, many neurochemical systems mediating responses to fearful stimuli have been identified, and new technologies are advancing the study of the interactions of these brain regions with one another. There is also active investigation regarding the relationship between genes and the environment in the development of chronically dysregulated anxiety with the hope that characterizing the neurobiology of anxiety will bring forth therapeutic advances that reduce the significant burden and long-term functional impairment associated with anxiety disorders.