 During May and June 2005 Ricardo Vásquez, an archaeologist from the Museo Nacional de Costa Rica, and Dr. Claude Chapdelaine with a group of his students from the University of Montréal, Canada conducted an archaeological field-school.Their work focused on a area of the central sector of Las Mercedes.By the end of the field-school, the team's stratigraphic excavations and mapping labors resulted in drawing of a general site plan, digital mapping of the most outstanding architectonic features, dating the site's earliest occupation to around 3,000 years ago, and the beginnings of carbon 14 based chronology for the site.