Phenomenological archaeologists and GIS scholars have turned much attention to visibility-who can see whom, and what can be seen-across ancient landscapes. Visible connections can be relatively easy to identify, but they present challenges to interpretation. Ancient peoples created intervisible connections among sites for purposes that included surveillance, defense, symbolism, shared identity, and communication. In the American Southwest, many high places are intervisible by virtue of the elevated topography and the open skies. The Chaco phenomenon, centered in northwestern New Mexico between A.D. 850 and 1140, presents an ideal situation for visibility research. In this study, we use GIS-generated viewsheds and viewnets to investigate intervisible connections among great houses, shrines, and related features across the Chacoan landscape. We demonstrate that a Chacoan shrine network, likely established during the mid-eleventh century, facilitated intervisibility between outlier communities and Chaco Canyon. It is most likely that the Chacoans created this network to enable meaningful connections for communication and identity. We conclude that the boundaries of the Chaco phenomenon are defined in some sense by intervisibility.