Social anxiety disorder is a common and debilitating disorder, often leading to complications such as depression, substance abuse and increased suicide risk. During the past two decades, research on the cognitive, behavioral, interpersonal and physiological aspects of social anxiety and subsequent theoretical models have greatly increased our understanding of the nature and maintaining factors for social anxiety disorder. Well-validated assessment procedures including self-report, interview and behavioral measures, are now available. Therapeutic exposure, typically combined with cognitive interventions, is the most established evidence-based treatment. Comparisons of psychosocial treatment to pharmacotherapy and some promising innovative treatment approaches are discussed as well. Emerging work on mechanisms of change suggest that changes in judgments about the probability and costs of negative outcomes are key to clinical change. Competencies for clinicians include expertise with basic cognitive and behavioral therapies, therapeutic exposure and adaptations for the unique characteristics of social anxiety disorder. Especially important is the impact of socially anxious individuals’ fears in interpersonal relationships on the therapeutic relationship. Expert competencies include treatment of more severe cases, overcoming extreme social isolation, complex presentations and social anxiety disorder that presents within the context of serious mental illness. Working in a multicultural context, particularly with language differences and sexual minorities are also discussed. Transition to expert competency relies on traditional educational venues, written material and utilizing expert consultation that is available on electronic venues.