Children live in a world dense with actions, objects, people, and events. Through time these phenomena provide the structure for development and the ingredients that help determine its course. In this chapter attention will be given to various aspects of the houses children live in and the natural and built environments surrounding them, with a view to explicating how each is implicated in children's behavior and development. The chapter begins with a consideration of several conceptual frameworks that bear upon how children might experience the structures, objects, and sensory stimuli in places where they spend time and what those experiences might mean for their health, competence, and adaptive functioning. Thereafter is a review of what is known about various aspects of housing conditions, the materials and facilities within the house, and the nearby physical environment, with attention to how each may affect children's behavior and well‐being. The third section moves beyond a consideration of particular aspects of the environment to a consideration of overall environmental chaos (i.e., how the structure of events and conditions in space and time affect health and behavioral tendencies). The chapter concludes with an effort to put issues pertaining to the physical environment in historic context, with a view to the future.