Because of its critical location as a landbridge linking North and South America, Panama has been an area of intense interest to climatologists, biologists, anthropologists, geographers, and other scientists trying to reconstruct and interpret the distribution and movements of plants, animals, and people in the Americas. Because movements of species have been influenced by the limited number of natural environments on the isthmus, and because climatic changes have altered the mix of environments dramatically over the last few dozen millennia, reconstructing the environmental history of Panama is a critical facet of research for a broad range of inquiries into the paleoecology and paleoanthropology of the Americas. This project is part of a larger, integrated effort to gather and interpret evidence that will substantially improve knowledge of the environmental history of Panama. Sediment cores have been gathered from lakes and bogs in scattered parts of Panama, two sets of which provide especially good records over periods as long as the last 26,000 years. This project will focus on analyzing the two sets of cores in laboratories, using pollen, diatoms, and phytoliths in the cores to reconstruct the range of species present in the vicinities of the core sites. These data will be integrated with data from other sites to develop more complete records of environmental change in Panama than have been available before. The enhancement of the data-based environmental history of Panama that will result from this project is significant in its own right, but it also will assist scholars in many other lines of inquiry. More accurate reconstructions of vegetational change will permit climatologists to refine regional climatic histories, which will help arbitrate current theoretical debates regarding the nature of post- glacial climatic change. Biologists and biogeographers will have more detailed data for their analyses of the migration of species and the character of response to environmental change. Anthropologists will find the data useful for better determining the timing and location of human occupancy through the presence of pollen and phytoliths of domesticated plants. This project therefore provides opportunities for increasing knowledge in a broad range of sciences.