Despite a training program to help veterans administration (VA) clinicians implement evidence-based psychotherapies (EBPs) for posttraumatic stress disorder (PTSD), uptake has been limited. To understand clinicians’ implementation challenges, we performed thematic analysis of semi-structured telephone interviews guided by the Promoting Action on Research Implementation in Health Services framework. Our sample included 22 psychotherapists in VA PTSD clinics in one region. We identified a theme not captured by our implementation framework: clinicians’ perceptions about their patients’ readiness for treatment. Clinician perception of patient readiness may be important to the uptake of EBPs and should be considered in mental health implementation work.