Multiple lines of evidence are presented to address questions surrounding the origins, antiquity, and role of maize in coastal Ecuador and western South America. A new methodology for tracing the use of maize using opal phytolith assemblages from food residues in utilized ceramics is introduced, and compared and contrasted to previous palaeoethnobotanical techniques. A total of ten carbon residue samples from the interior surfaces of excavated pottery from the Valdivia site of La Emerenciana, were examined for the presence of maize opal phytoliths. The carbon residue samples were derived from archaeological features consisting primarily of architectural remains, ritual offerings, and funerary deposits excavated from an earthen platform mound. Laboratory results indicate that three of the ten samples analysed contain phytolith assemblages representative of maize cob chaff. All of the samples are derived fro a stratigraphic layer radiocarbon and AMS dated to between c. 2400 and 1650 BC. Measurements of radiocarbon assays and AMS dates from residue samples are calibrated and then evaluated to provide a more accurate relative chronology for the introduction of maize at La Emerenciana. Results from these various lines of evidence all support an introduction of maize into coastal Ecuador at approximately 2200-1900 cal BC. The implications of these data are briefly reviewed with regard to previous research on the importance and role of maize to pre-Hispanic socio-cultural development. Our conclusions indicate that contrary to previous assumptions, maize was initially a secondary plant in the Valdivia subsistence economy and maintained a cultural, as well as economic significance to Andean socio-cultural development.