Recent chemical analyses of ancient anthrosols in Mesoamerica and elsewhere demonstrate the explanatory value of these investigative techniques and also point out some of the problems that challenge interpretive capabilities. This paper presents the results of phosphate and heavy metals analyses of soils in residential areas at Piedras Negras, Guatemala, and offers some preliminary interpretations of the patterns obtained. After a brief review of recent studies of soils in archaeological contexts, we discuss some of the merits and problems with using different sampling designs and with obtaining reference samples that help model distributions of chemical concentrations. To aid in interpreting domestic activities, soil analyses are combined with archaeological data produced from both large-scale clearing and smaller test units. In this way, phosphate concentrations implicate refuse disposal areas, and heavy metal signatures and their patterning suggest that urban Maya houses may have been painted with metal-based mineral pigments. Varying, relative proportions of phosphates and heavy metals in midden deposits indicate the probability of classifying such features according to chemical signatures. We argue that this combined approach offers greater clarity in discerning activity patterns in residential environments than investigations that do not incorporate soil chemical analyses.