This thesis is an analysis of invertebrate fauna from Mission-era (ca. AD 1565-1680) shell middens on St. Catherines Island, Georgia, which contributes to archaeological inquiries into population aggregation, community organization, and indigenous foodways at Pueblo Santa Catalina de Guale. Zooarchaeological and stable isotope analyses of bulk samples of shell midden matrix from five Mission-era residential neighborhoods at Pueblo Santa Catalina de Guale are used to explore invertebrate animal use, season of capture, and habitat exploitation. The summed Mission-era results are contrasted with similar data from the pre-Hispanic Irene Period (AD 1300-1580) (Bergh 2012) on St. Catherines to assess change and continuity in shellfishing practices during missionization. Reduced reliance on eastern oysters (Crassostrea virginica) relative to other mollusks, increased seasonal restriction in oyster collection, and increased intra-site variability in animal use on St. Catherines Island were indirect consequences of Spanish colonialism. The assemblages from each Mission-era neighborhood are compared to one another and considered in combination with previous vertebrate faunal (Reitz and Duke 2008, Reitz et al. 2010, Reitz 2016) analyses to closely examine intra-site variability. Population aggregation of towns from along the coast at Pueblo Santa Catalina created a pluralistic indigenous community with multiple culinary communities of practice. This is linked to increased variation in vertebrate and invertebrate animal use from the Irene Period at Meeting House Field (Bergh 2012) into the Mission era at Pueblo Santa Catalina de Guale.