Generalized anxiety disorder (GAD) is a chronic disorder that has been associated with significant psychosocial impairment, as well as health-care utilization/cost. Further, it is a highly comorbid disorder, and has been posited to be the basic anxiety disorder, which increases vulnerability for other anxiety and mood disorders. Despite the significant health impact of this disorder, it is currently the anxiety disorder for which existing treatments have demonstrated the least effectiveness. Cognitive-behavioral treatments have demonstrated the most efficacy to date; yet studies commonly find that less than half those treated meet criteria for high end state functioning after a follow-up period, indicating that more work is needed in treatment development for this disorder. Current theory and research in the area of worry and GAD highlights the role of cognitive/experiential avoidance in this disorder, suggesting that an integrative treatment that combines elements of traditional cognitive-behavioral approaches with mindfulness/acceptance-based elements from other behavioral treatments may be particularly efficacious with this population. The current application aims to further develop and refine this integrative therapy (Behavioral Mindfulness and Action Therapy for GAD; BMAT-G), develop reliable adherence and competency ratings for the therapy, and pilot the intervention by comparing BMAT-G to a wait list control group. The first phase of the study will focus on treatment development. Thirty-two clients will be treated with this new treatment and the manual will be refined through client, therapist, investigator, and consultant feedback. At the same time, adherence and competency ratings will be developed and raters will be trained to reliably administer them. Finally, thirty-two clients with a principal diagnosis of GAD will be randomly assigned to receive the newly developed intervention, or to a 14-week waitlist condition. Therapeutic gains will be assessed in several domains: anxious and depressive symptomatology, associated features (e.g., cognitive avoidance), and quality of life. Data from this development grant will be used to prepare a large-scale treatment outcome study that explores whether the addition of acceptance-based elements incrementally improves outcomes in both symptom report and broader functioning.