We aim to (1) evaluate the effectiveness of cognitive therapy and paroxetine and their combination, (2) investigate the patterns of change and the mechanisms of action involved during treatment by using psycho-physiological assessments in order to delineate some of the cognitive, behavioural and physiological mechanisms in the patients' response to CT, to paroxetine and placebo.One hundred patients with a primary diagnosis of social phobia will be selected and randomised into four treatment conditions. The first group (N=25) will be treated with CT alone, the second group (N=25) with CT plus paroxetine, the third group (N=25) with paroxetine and clinical management (TAU), the fourth group will receive placebo and clinical management (N=25). All patients will have 12 weeks of treatment in the acute phase, which includes 12 sessions of individual treatment for the two first groups. The 2nd and 3rd groups will in addition have 12 weeks of drug treatment in the maintenance phase. The 4th group will have placebo for 24 weeks and clinical management. The patients will be assessed at pre-treatment, at 12 weeks and at the end of treatment of the acute phase (12 weeks) and by the end of maintenance phase (24 weeks). Follow-up will be at 6 and 12 months.

Measures are based on all three main sources; self-report inventories, clinical assessments by independent raters and psycho-physiological assessments.