He is a past president of the Society for American Archaeology and past secretary of the Archaeology Division of the American Anthropological Association. He has been a distinguished lecturer at UCLA, Washington State University, University of Colorado, and the University of Tennessee, as well as the University of Leiden (Netherlands) and the Universities of La Plata and Cordoba (Argentina). He has served on both the National Science Foundation and Wenner-Gren proposal review panels.

Kelly has worked on the archaeology, ethnology, and ethnography of foraging peoples since 1973, working on archaeological research projects in Nevada, California, New Mexico, Kentucky, Georgia, Chile and, for the past 13 years, Wyoming. He has conducted ethnographic work with part-time hunter-gatherers in Madagascar and assisted in an ethnohistory project in Micronesia. After coming to Wyoming, he returned to an early interest in paleoindian archaeology, researching the Pine Spring site in southwest Wyoming, and, for the past 10 years, many of the caves and rockshelters that George Frison excavated in the 1970s in the Bighorn Mountains. This year he begins a project in Glacier National Park that will survey the park's ice and snow patches for artifacts exposed by recent global warming. The project aims to use this evidence to relate current to past climate changes.