Returning veterans from Iraq and Afghanistan (OIF/OEF veterans) have a very high incidence of TBI (14-23%) with the largest number having mild TBI (i.e., no discernible structural brain damage) with 63.5% having persistent headache. Treatment of PTH in this population has been difficult and mind/body interventions including Mindfulness Based Stress Reduction (MBSR) may offer significant benefit. A biomarker that will support clinical endpoints ("surrogate endpoint") and help predict clinical benefit, could be used to more efficiently and completely assess mind/body treatment effects in clinical trials for PTH, compare various complementary and alternative medicine (CAM) treatments, and potentially target specific treatments to patients most likely to benefit. This project aims to investigate candidate biomarkers for MBSR response in veterans with PTH. Primarily, all subjects if they are interested and appropriate for the study, will undergo a screening at their regular clinic visit at the VAGLAS physical medicine and rehab department. If a subject responds to advertisement they will be screened using the same tools and enrollment criteria required for the veterans at VAGLAS. We expect we will need to enroll and screen no less than 33 subjects in order to complete 20 evaluable subjects for analysis. The study subjects will be evaluated for the severity of their PTH, the impact of PTH on their life, and the extent of the disease/pain condition. If eligible the nurse coordinator will contact them to schedule the pre-MBSR functional MRI visit. At the MRI we will evaluate patterns of activity (functional connectivity) in the brain at rest, and look at cortical thickness. Following the MRI visit all subjects will complete a 9-week modified MBSR training with a qualified instructor. Mid-study (after MBSR class 4) the subject will be asked to complete mid-study questionnaires at home on Survey Monkey or on paper if they choose. At the end of the MBSR training in which the subject will have to complete at least 3 visits, functional (f)MRI procedure will be repeated and compared against the first. Three months after completing the study there will be a follow-up visit to complete behavioral/symptom/quality of life questionnaires on line via SurveyMonkey. This is to see if the changes in the biomarkers will mediate changes in these behavioral measures 3-mo post Treatment (i.e. measure stability).