Over the decades, 3,4-methylenedioxymethamphetamine (MDMA) users have devised numerous harm reduction strategies to minimize adverse effects, including drug testing and preloading/postloading of vitamins and psychotropics. The latter has evolved from subcultural capital traded on internet forums into commercialized kits (e.g., Rollsafe, RaveBOX) without substantial data. Prior surveys have revealed that enthusiasts are eager to learn, employ, and share knowledge, signifying a critical need for thorough investigation of these agents, particularly as serious drug interactions can occur. As MDMA is largely unavailable for clinical investigation, anonymous self-reporting remains a powerful investigational tool. Here, we briefly review the history of supplementation in MDMA use and reveal a new, web-based, self-administered tool that uses snowball sampling to collect anonymous data on preloading/postloading with unprecedented depth and scale. Designed with input from clinicians and a focus group of MDMA users, the tool aims to: 1) explore attitudes and motivating factors of MDMA users for supplementation; 2) categorize the wide variety of preloading/postloading substances in implementation; and 3) identify associations between specific regimens and perceived benefits. Items will be controlled for a wide variety of demographic, medical, and psychiatric factors. Overseen by senior MDMA researcher, Dr. Charles Grob, this ongoing study is the most rigorous examination of the subject to date. In addition to reviewing preliminary data, the investigators welcome stakeholder discussion from the international community to guide future data applications. Ashley Covington, M.D. is a fourth year resident in psychiatry at UCLA/Semel Institute and currently the program training chief. She received her medical degree from Penn State College of Medicine where she completed work in the associations between sleep patterns and adolescent suicide. Her research interests include holistic and integrative medicine, mind-body connection, resilience, and psychedelic-assisted psychotherapy. Adrienne Grzenda, M.D., Ph.D. is a third year resident in psychiatry at UCLA/Semel Institute. She received a doctorate from Mayo Clinic in biochemistry and molecular biology, publishing extensively on epigenetic mechanisms of histone methylation in long-term gene repression. She also completed an M.S. at University of Minnesota in bioinformatics and computational biology. Herresearch employs biostatistical modeling of large, multidimensional datasets (e.g., genetic, epigenetic, epidemiologic) to answer questions about complex psychiatric conditions and phenomena.