With a lifetime prevalence of approximately 17% among community-dwelling adults, anxiety disorders are among the most pervasive of contemporary psychiatric afflictions. Traditional Cognitive Behaviour Therapy (CBT) is currently the first line evidence-based psychosocial intervention for the treatment of anxiety. Previous research, however, has found that a significant proportion of patients do not respond to traditional CBT or exhibit residual symptomatology at treatment cessation. Additionally, there is a paucity of evidence among child populations and for the comparative effectiveness of alternative interventions. Acceptance and Commitment Therapy (ACT) has a growing empirical base demonstrating its efficacy for an array of problems. A systematic review was conducted to examine the evidence for ACT in the treatment of anxiety. PsycInfo, PsycArticles, PsycExtra, Medline and Proquest databases were searched, reference lists examined and citation searches conducted. Two independent reviewers analysed results, determined study eligibility and assessed methodological quality. Thirty-eight studies met inclusion criteria (total n=323). The spectrum of DSM-IV anxiety disorders as well as test and public speaking anxiety were examined. Studies were predominantly between-group design and case studies, with few employing control comparisons. Several methodological issues limit conclusions; however results provide preliminary support for ACT. Larger scale, methodologically rigorous trials are needed to consolidate these findings