Study Design: We will develop a manual for our meditation incorporating input from qualitative data from patients and an expert advisory board including meditation and PTSD therapy experts. We will adapt a present-centered therapy group as a control intervention, controlling for hours of therapist contact. We will randomly assign PTSD patients to either meditation or present-cetnered therapy, with pre- post, 3 mo, and 6 mo follow-up assessments with validated measures of PTSD and psychiatric symptoms, quality of life, "mindfulness", emotional regulation, and trauma-related maladaptive cognitions. We will also perform a pilot study of fMRI neuroimaging to determine the effects of meditation on neurocircuitry underlying emotional regulation that may mediate therapeutic effects. Validated emotional and social cognition neuroimaging paradigms will be used to examine specific effects of mindfulness meditation on mPFC and cortico-limbic neurocircuitry.