[2][3] Fash currently holds the position of Bowditch Professor of Central American and Mexican Archaeology and Ethnology at Harvard and was previously Chair of the Anthropology Department and the Director of the Peabody Museum.
In 1975, Dr. Fash excavated at Grasshopper, Cibecue, Arizona as a student in a summer field school, although, he is most noted for his work on the Maya site of Copan, Honduras.
[9][10][12] In 1987, Fash was awarded a Fulbright Senior Research Fellowship for this project, whose purpose is "to record and protect Copan’s hundreds of stone mosaic sculptures.
"[5][10] To give an idea of the extent of the project, involves all of Copan's Principle group and preservation of its Hieroglyphic Stairway.
[10] Harvard Field School in Maya Archaeology at Copan, Honduras – Fash directed this project for 6 years.
[9][14] From 2000 to 2003 he co-directed Xalla Palace Project at Teotihuacan, Mexico, with Leonardo López Luján and Linda Manzanilla.
[18] He served as Interim Director of The Programa Integral de Conservacion del Parque Archeologico Copan, one of the conservation efforts that involve the participation of several organizations including the Honduran Institute of Anthropology and History, Harvard University, the Getty Conservation Institute, and UNESCO.