Tlacuachero is the site of an Archaic-period shellmound located in the wetlands of the outer coast of southwest Mexico. This book presents investigations of several floors that are within the site's shell deposits that formed over a 600-800 year interval during the Archaic period (ca. 8000-2000 BCE), a crucial timespan in Mesoamerican prehistory when people were transitioning from full-blown dependency on wild resources to the use of domesticated crops. The floors are now deeply buried in an limited area below the summit of the shellmound. The authors explore what activities were carried out on their surfaces, discussing the floors' patterns of cultural features, sediment color, density and types of embedded microrefuse and phytoliths, as well as chemical signatures of organic remains. The studies conducted at Tlacuachero are especially significant in light of the fact that data-rich lowland sites from the Archaic period are extraordinarily rare; the wealth of information gleaned from the floors of the Tlacuachero shellmound can now be widely appreciated.