Sunset Mesa Ruin lies near the confluence of the Rillito and Santa Cruz Rivers in the northern Tucson Basin. First recorded in the late 1930s by Frank Midvale, the site contains two components: a prehistoric Rincon phase Hohokam settlement dating between A.D. 1000 and 1100 and a historical-period component centered on a three-room adobe dating to the late nineteenth century. Much of the report focuses on Rincon phase settlement and subsistence. The authors use data collected from the excavation of a discrete residential cluster of five pit houses to document a sequential series of small courtyard groups. Excavation of a canal segment provides the authors the opportunity to investigate Hohokam irrigation practices in the Tucson Basin, which differ dramatically from their better-known counterparts in the Phoenix Basin.