Intrusive thoughts, flashbacks, panic attacks and sudden physiological arousal are each experienced as involuntary, are difficult to control, and lead to considerable distress. Such observations have led to the suggestion that anxiety disorders are associated with the operation of automatic information-processing biases. Clinical and experimental evidence for this proposal is reviewed and three different classes of routes to the development and modification of these automatic processes are described: an innate route, repetition/habituation, and conscious appraisal. The review focuses in particular on the third route, proposing that automatic processing biases can be altered by accessing and modifying conscious appraisals of internal and external events. Indirect evidence is provided by selective attention paradigms in anxiety, treatment studies and clinical observations, although further research will be necessary for a direct test of the pathway. The implications for the theory and practice of psychological therapy for anxiety disorders are described.