Environmental psychologists study how natural and built environments affect human behavior and psychological processes as well as what people think, feel, and do about those environments (Gifford, 2014). In view of the ongoing rapid and detrimental anthropogenic changes to the natural environment, such as climate change and biodiversity loss, robust, visible, and applicable psychological knowledge is needed to inform societal transformations of human-environment transactions. With Environmental Psychology Open (EPO), we present a new and freely accessible platform for the communication and discussion of such knowledge.