This chapter provides an empirical review of the nature and treatment of social phobia and specific phobias, the two most common anxiety disorders. Definitions of social and specific phobias are followed by a review of assessment methods, epidemiology, comorbidity patterns, course, differential diagnosis and differences in developmental, gender, and cultural presentations. An overview of etiology and pathophysiology focuses on biological factors (e.g., genetics, neurobiology), social/environmental factors, and psychological factors including learning and conditioning perspectives, as well as personality and cognitive variables related to the development and maintenance of the disorders. Treatments for social phobia and specific phobias are reviewed, including both somatic and psychosocial interventions. Factors influencing treatment process and outcome are discussed.