The anxiety disorders are a collection of disorders characterized by psychological fear and anxiety and somatic manifestations of fear and anxiety (4th ed., text rev.; DSM-IV-TR; Diagnostic and Statistical Manual of Mental Disorders; American Psychiatric Association, 2000). Anxiety disorders can significantly impair a sufferers overall wellbeing and result in significant individual and societal economic burden. Exposure therapy has been proposed to be a core component of anxiety disorder treatment. However, up to 50% of those who are successfully treated experience return of fear after therapy, which may act as a precursor of complete clinical relapse. Spontaneous recovery, reacquisition, reinstatement, and renewal may be four contextually driven mechanisms that can predict return of fear. Renewal, the most widely studied of these mechanisms, was the predominant focus of the current thesis. Renewal of fear occurs when post-therapy encounters with feared stimuli take place in contexts that are different to the treatment context.