Humans live in a rich, vibrant, and dynamic world that both elicits and affords behavior, not only within the environment, but also with other human beings.  Until recently, it has been particularly challenging to obtain state of the art measures of behavioral and neurophysiological activity in natural environments (i.e., outside of laboratory conditions).  As a result, researchers have been forced to constrain much of their work to traditional low-fidelity lab-based studies  In UCF IMMERSE, we tear down the wall between lab-based behavioral and neurophysiological research and the real world by employing the latest generation of ambulatory behavioral and neurophysiological measurement tools to study humans where they exist: either in the physical world itself or in very close approximations to it. Importantly, our work considers not only humans acting in isolation, but also in small groups as they do in a range of situations, including many that are relevant to military contexts.  To do so, we use an array of virtual reality, augmented reality, mobile eye tracking, ambulatory EEG, and ambulatory physiological recording systems to solve real-world problems.  Critically, all of these systems can be combined to provide multiple measures of human performance (e.g., brain activity, physiological arousal, eye gaze) in virtual and real-world settings, creating a host of new and unparalleled capabilities for researchers interested in solving practical, real-world problems.