Although social anxiety disorder (SAD) is a common and disabling disorder that may occur in different cultural settings, it is under-diagnosed by clinicians. In order to facilitate accurate diagnosis, the clinical features and differential diagnosis of SAD are described, together with useful assessment instruments for clinicians. Aetiological evidence suggests that the causal pathways for SAD include genetic, neurobiological, temperamental and cognitive factors. A range of effective treatments for SAD are available: current findings suggest that the selective serotonin reuptake inhibitors (SSRIs) are the first-line choice of pharmacotherapy for SAD, while several other agents show promise in treating refractory cases; furthermore, SAD responds well to psychotherapeutic interventions such as exposure therapy and cognitive restructuring.