The flourishing positive psychology field has Flow as a core construct. This systematic review of 185 articles examines Flow's concept, to analyse it theoretically, methodologically, empirically, and to provide an agenda for Tourism research. This paper adds to the knowledge in tourism psychology by exploring the Flow framework's core elements, incorporating its drivers, processes and outcomes, as an instrument to improve tourists' experiences. The study suggests the relevance of considering the tourist's characteristics and both the positive and negative outcomes of the Flow experience and other concepts, such as immersion or cognitive stimulation. Extant studies often use the Flow state scale as a measurement tool, but new opportunities are offered by using physiology instruments. Several propositions are put forth to foster the investigation on Flow in the tourism field, and to further the understanding of the tourists' behaviour and experience.