This study will compare a 16 week psychotherapy group for PTSD involving Mindfulness and Self-compassion meditation, with a more standard form of group psychotherapy known as "Present-centered group therapy". Both therapies will be conducted at the VA Ann Arbor PTSD clinic by VA psychotherapists. (The study is also approved by the IRB of the VA Ann Arbor). Combat veterans will be randomly assigned to either the Meditation or the standard group psychotherapy. All patients will also receive fMRI brain scans before and after the therapy, as well as assessment interviews before, at 8 weeks, and immediately post-therapy, and at 3 mo and 6 mo follow-ups. Saliva cortisol and measures of attention will also be obtained at each assessment.