Radiocarbon dates largely obtained from bulk soil samples in 24 soil profiles in the Teotihuacán Valley, Mexico, are reported insofar as they represent a first step towards developing a sequence of soil formation, erosion, vegetation change, and human impact during the Holocene. Limitations of 14C dating in the area are considered, particularly the absence of charcoal in sediments and poor preservation of pollen. A broad temporal scheme is proposed to guide future research in which 4 periods are defined: ∼5000–2000 BP (relative stability with short, intermittent episodes of erosion); ∼2000–1500 BP (erosion-sedimentation, deforestation, and intensive agriculture); ∼1500–1000 BP (relative stability, depopulation, and partial recovery of the landscape); and ∼1000–500 BP (erosion-sedimentation, deforestation, and intensive agriculture).