This thesis assesses climate change during the Hypsithermal Climatic Interval through the analysis of freshwater mussel remains from archaeological sites in Eastern North America. Modern climate data was used as a model to test the mosaic consequences of climate change. Freshwater mussels: can be used as indicators of precipitation by examining changes in overall size through time: larger mussels are found in larger streams, while smaller mussels are found in smaller streams. This study combines morphometric and isotopic data from archaeological freshwater mussels at Modoc Rock Shelter, Watson Brake, Plum Creek, Owens site, and Landerneau mounds to assess past climatic conditions. At Modoc Rock Shelter, oxygen isotopic data corroborate morphometric data and show that climate was fluctuating with a period of stability at the onset of the Hypsithermal. The oxygen isotopic data sets from the Louisiana sites show that the mid-Holocene was much warmer than the late-Holocene.