The paper examines the contribution of Dutch physiologist, biologist, psychologist, philosopher F. J .J. Buytendijk (1887–1974) to the philosophical and scientific study of play, his methodological innovations, and their reception. Key aspects of his approach are analyzed: the priority of embodiment and affectivity as pre-reflective modes of relatedness to the world; the principle of reciprocity between the player and the play object; and a critique of utilitarian and evolutionist accounts of play. A brief biography of Buytendijk is provided. Special attention is given to the early period of his research, including his turn from zoopsychology to a phenomenologically oriented anthropology under the influence of Aristotelian-Thomistic natural philosophy. Emphasis is placed on the concepts of the pathic mode of being, the ‘functional circle’, and the image-character (Bildhaſtigkeit) of the play object, which together allow play to be viewed as a fundamental, primary way of being-in-the-world of the living. The paper demonstrates the connection between his ideas and J. Huizinga’s subsequent theory of play. The article seeks to broaden the view of Buytendijk as an interdisciplinary thinker and to show the significance of his research for a contemporary philosophical understanding of play.