This chapter considers the advantages of islands as analytical units and the benefits of multi-proxy approaches to diet reconstructions. An overview of some common historical trends in Pacific Island diets is provided, followed by more detailed examination of two southern Cook Island sequences (Mangaia and Aitutaki Islands) in Polynesia, localities which were settled by closely related peoples but offered different dietary opportunities given their contrastive geographies. Archaeofaunal, archaeobotanical, and stable isotope records are used to explore dietary variability on these two islands over an approximately 750-year period. The analysis emphasizes the relationships between different dietary components (terrestrial foraging, marine exploitation, and evolving agroeconomies) and the dynamic feedback relationships that can shape dietary change.