This trial compares two psychotherapies, Acceptance and Commitment Therapy (ACT) and Present Centered Therapy (PCT), for veterans of the conflicts in Iraq and Afghanistan. We hypothesize that ACT will be more effective than PCT at reducing emotional distress and improving functioning. We further hypothesize that both interventions will be highly acceptable to participants.

The proposed study is a randomized controlled trial (RCT) of Acceptance and Commitment Therapy (ACT) as compared to a control psychotherapy, Present Centered Therapy (PCT), for individuals with distress and impairment who deployed as part of Operation Enduring Freedom and/or Operation Iraqi Freedom (OEF/OIF). ACT was selected for study because it has a number of advantages for this population. It is not tied to any particular symptom constellation, so it can be applied to a variety of presenting concerns (Hayes, Luoma, et al., 2006; Öst, 2008, Powers et al., 2009), resulting in reduced training burden for clinicians and less need for applying sequential treatments to address co-morbidities. ACT has good face validity (i.e., "it makes sense") and conveys a compelling message to young Service Members and Veterans. ACT asks individuals to move forward in accordance with one's values regardless of limitations rather than struggling against those limitations. ACT appears to be acceptable to patients (mean attrition of 15.4% in 13 RCTs (Öst, 2008). ACT is being widely disseminated without adequate evidence of its effectiveness for this important population.

Inclusion Criteria:

• Previous deployment to OEF or OIF
• Current distress and impairment [at least one Diagnostic and Statistical Manual version IV (DSM-IV) anxiety or depressive disorder as determined by the Mini International Neuropsychiatric Interview (MINI) or post-concussive symptoms (PCS) as determined by a positive traumatic brain injury (TBI) screen with a score of 25 or greater on the Rivermead with distress or impairment related to PCS].
• Capable of giving informed consent.

Exclusion Criteria:

• Cognitive impairment that would interfere with treatment. Potential participants will be excluded if they screen positive for more than mild cognitive impairment on the Montreal Cognitive Assessment (MoCA; excluded if score < 26).
• Severe psychopathology (psychosis, bipolar illness, urgent suicidality or self-injurious behavior) or untreated substance dependence in the past month.
• Anticipated change in pharmacologic intervention. Patients may stay on their current medications during the study but will be asked to refrain from beginning or altering medication use during the study to the extent possible.
• Other psychotherapy focusing on the same target symptoms. Patients may attend self-help groups or treatment for other types of problems (e.g., couples counseling) but not other treatment for the same presenting problems.
• Anticipated deployment or other circumstance that would interfere with completion of all study procedures.

12 weeks