Social evolutionary transformation involves and affects all levels of human society, including households. The formation of a state-level society at the Tilcajete sites has been documented through extensive horizontal excavations focused on the civic-ceremonial buildings at a two Formative Period sites in the southern branch of the Oaxaca Valley. This paper presents findings from 2 seasons of work in 2014 and 2016 focused on the residential sectors at El Mogote, occupied during the Early Monte Albán I phase (500-300 B.C.) and El Palenque, occupied during the Late Monte Albán I phase (300-100 B.C.). I examine residential variability within each site as well as change through time. I argue that the timing and nature of changes to residential architecture, activities, and assemblages reflect the dynamic role household decisions played in the sociopolitical transformations at the sites.