This chapter examines three churches designed in 1957–61 by regionally significant architects in which structural and material explorations transform the sanctuary wall into a diaphanous screen. Exposed systems of precast concrete, steel, and glulam wood are assembled in ways that are simultaneously robust and refined. Light is a major component of each system, so that the upright posture of the wall yields to a poetics of lightness rather than gravity. This chapter argues that the tectonics, materiality, and spatial complexity of these sanctuary walls inflect unmistakably modern compositions towards being unique expressions of the humanist stance of the Unitarian denomination and the optimism of post-war suburban America. Structural innovation was coupled with a desire for a vivid presence of light as a manifestation of nature.