Trauma-focused psychotherapies such as cognitive processing therapy (CPT) and prolonged exposure (PE) are some of the most effective treatments available for posttraumatic stress disorder (PTSD). These treatments have been widely disseminated and promoted throughout the VA Health care System. However, adherence to and completion of these protocols among veterans is often poor, resulting in diminished impact. "Support persons" (SPs) such as relatives and close friends may provide a source of emotional or practical support in treatment, but little is known about how SPs are involved in or exposed to treatment principles and activities. The primary goal of the current research was to examine the experience of SPs of veterans who had poor adherence to treatment. We were interested in SPs' knowledge about the treatment, their level of involvement in treatment activities or sessions, and their potential interest in more participation or education. Qualitative analyses were used to examine data collected from interviews with 19 SPs of veterans who had an unsuccessful course of CPT or PE. Results indicated generally very low levels of knowledge and treatment participation. However, among most SPs there was substantial interest in the possibility of more treatment involvement, particularly in order to receive guidance from the clinician about how to respond to the veteran's symptoms. We suggest that it is possible and desirable to incorporate loved ones more formally into such protocols. (PsycInfo Database Record (c) 2021 APA, all rights reserved).