This Element examines how archaeology can contribute to the investigation of ancient wealth disparities, using the Jōmon and Yayoi periods in Japan as a case study. It analyzes 1,150 pit dwellings from 29 archaeological sites in southern Kantō, dating from the Late Jōmon to the end of the Yayoi period (ca. 2540 BC–AD 250). Household wealth is estimated through pit dwelling floor area, with Gini coefficients calculated for each site. Results show relatively low inequality in the Late Jōmon, a slight decline in the Middle Yayoi, and a marked rise in the Late Yayoi period. Notably, average floor area decreased in the Late Yayoi period. These patterns raise broader questions about how wealth disparities were shaped by communal norms, settlement organization, the rise of agriculture, and expanding trade networks involving iron tools. This research underscores archaeology's unique ability to illuminate long-term economic transformations.