Despite the growing interest in expanding the joint use of K–12 public schools by public health and planning practitioners to promote healthy, sustainable communities, the topic has received little attention in the urban planning and public health scholarship. The objective of this article is to situate joint use in the academic literature focused on the links between built environments and health. I examine the “state of the field” of K–12 joint use through studying the academic and associated literature, interviews, participant observation, and case examples. I develop a joint use classification system to aid researchers and practitioners.