Few randomized controlled trials have directly compared the effects of mindfulness and acceptance-based MBSR and reappraisal-based CBT in the treatment of anxiety disorders. In the current study, we propose a randomized pilot study that compares MBSR and group CBT to enable a direct assessment of training in reappraisal and mindfulness-based emotion regulatory strategies, and their role in diminishing primary anxiety disorders and improving attention regulation. The study will be conducted with veterans at the San Diego VA Medical Center Anxiety Disorders Clinic. We aim to recruit 60 participants and randomize half to each group treatment. The study has three central aims: 1) Assess the efficacy of MBSR and group CBT in treating anxiety disorders among military veterans; 2) Evaluate the extent to which reappraisal and acceptance/mindfulness emotion regulation strategies are acquired in CBT versus MBSR; 3) Investigate the degree to which CBT and MBSR improve basic attention regulation processes via computerized cognitive attention tasks. Relatedly, we aim to assess the degree to which changes in attention regulation are associated with improvements in cognitive reappraisal and mindfulness. By post-treatment we predict that participants will exhibit increases in use of the emotion regulation strategy associated with their assigned condition: reappraisal (for CBT) and mindfulness/acceptance (for MBSR). We also predict that improvements in (primary) anxiety disorder severity and attentional tasks will be associated primarily with shifts in reappraisal for CBT, and greater use of mindfulness/acceptance for MBSR.