To understand the effects of European contact on the organization, size, and mobility of Pueblo populations in the Southwest requires detailed knowledge of the occupational histories of the aggregated settlements that typify the late prehistoric and early historic record. Unfortunately, such understanding is generally lacking because the methods used to document occupational histories of settlements tend to either obscure fine-grained temporal distinctions or necessitate costly, and politically objectionable, large-scale excavations. To overcome these difficulties, we use surface expressions to analyze the occupational and population history of San Marcos Pueblo (LA98), an aggregated, late prehistoric site in the Galisteo Basin of New Mexico that persisted to the Pueblo Revolt of 1680. Field methods include detailed mapping of the settlement and systematic surface collections of middens. Frequency seriation, correspondence analysis, and mean ceramic dates of decorated ceramic rims comprise our principal analytic methods and demonstrate that the pueblo was abandoned four times before 1680. Causes of abandonment are discussed. Relative scale measures of population show demographic fluctuations with maximum aggregation during the fifteenth century. Despite demographic pulses, the pueblo remained vital until the terminal abandonment.