Have you ever passed a sign on the road advertising for something called "Kratom"? or, perhaps, a friend or family member has mentioned trying it. What is it? An herbal supplement, or pharmacological drug? As addiction scientists, epidemiologists, and clinicians, do we have anything to be concerned about? In this episode, Dr. Kirsten Smith catches us up on what is known about Kratom, including the pharmacology, effects, and prevalence of this emerging substance. Dr. Kirsten Smith is a Post-doctoral Fellow in the Real-world Assessment, Prediction, and Treatment Unit at the National Institute on Drug Abuse Intramural Research Program, and an incoming Assistant Professor at Johns Hopkins University.