Acceptance and Commitment Therapy (ACT) is an innovative acceptance-based behavior therapy that has been applied broadly and successfully to treat a variety of clinical problems, including the anxiety disorders. Throughout treatment ACT balances acceptance and mindfulness processes with commitment and behavior change processes. As applied to anxiety disorders, ACT seeks to undermine excessive struggle with anxiety and experiential avoidance--attempts to down-regulate and control unwanted private events (thoughts, images, bodily sensations). The goal is to foster more flexible and mindful ways of relating to anxiety so individuals can pursue life goals important to them. This article describes in some detail a unified ACT protocol that can be adapted for use with persons presenting with any of the major anxiety disorders. To exemplify this approach, we present pre- and posttreatment data from three individuals with different anxiety disorders who underwent treatment over a 12-week period. The results showed positive pre- to posttreatment changes in ACT-relevant process measures (e.g., reductions in experiential avoidance, increases in acceptance and mindfulness skills), increases in quality of life, as well as significant reductions in traditional anxiety and distress measures. All three clients reported maintaining or improving on their posttreatment level of functioning. (Contains 2 tables.)