Posttraumatic stress disorder (PTSD) is a devastating and life-altering disorder, and treatment outcomes from evidence-based treatments (EBTs) are mixed. The purpose of this systematic literature review was to suggest ways to enhance the efficacy of EBTs by critically evaluating the potential mechanisms of therapeutic action at work in MDMA-assisted psychotherapy to treat PTSD and applying this understanding to existing treatment protocols, without the administration of MDMA. Current APA and DoD/VA guidelines both strongly recommend three treatments for PTSD: Cognitive Behavioral Therapy, Cognitive Processing Therapy, and Prolonged Exposure. Despite a smaller research base, MDMA-assisted psychotherapy has shown evidence of high patient engagement, retention, and recovery rates in comparison to EBTs. Utilizing a systematic literature review, this study examined the three EBTs along with MDMA-assisted psychotherapy to compare treatment factors and outcomes, with the goal of uncovering therapeutic mechanisms of action that could be utilized to enhance EBTs. Pre-treatment factors, structural treatment factors, and the neurobiological effects of MDMA in the context of psychotherapy were analyzed. In addition, a comparison was made between these factors and the three EBTs, highlighting key similarities and differences. Four areas of divergence were identified as aspects of MDMA-assisted psychotherapy that could be utilized to enhance existing EBT protocols. These were introduced as the “PACT” Model: (1) Presence; (2) Acceptance; (3) Connection; (4) Transcendence. Findings from this study suggest that EBTs could be positively enhanced through incorporating certain non-pharmacological aspects of MDMA-assisted psychotherapy that may facilitate patient engagement and imply important therapeutic mechanisms of action.