This chapter provides an overview of psychological accounts of specific phobia and describes a standard protocol for in vivo exposure, the current treatment of choice for specific phobia. Specific phobia is one of the most common psychiatric disorders in the general population, with documented lifetime prevalence estimates ranging between 9.4% and 12.5%. Specific phobias frequently co-occur with other DSM-IV disorders as an additional diagnosis, particularly when the predominant diagnosis is an anxiety disorder or a mood disorder. Behavioral treatments for specific phobias are rooted in Mowrer's classic two-stage theory of fear development. The chapter examines the role of cognitive factors in specific phobia. Recent research suggests that visual and somatic mental imagery may also play a role in the maintenance of specific phobia. There are a number of challenges that clinicians and clients may encounter during exposure treatment for specific phobia.