Oceanic islands offer outstanding ‘model systems' for investigating long-term dynamics between human populations and their ecosystems. Whilst the state factors involved in human-environment dynamics on islands are often simpler than on continents, the same essential processes are involved. This paper applies a comparative approach to understanding the reciprocal interactions between a set of four Polynesian island cases (Tikopia, Mangaia, Mangareva, Hawaiian Islands), over time scales of between one and three thousand years (kyr). In all cases, the island ecosystems were colonised by Polynesian populations derived from the same ancestral culture, with similar socioeconomic patterns. However, the ecosystems vary significantly in scale, geologic age, and other characteristics. Comparing the historical trajectories of these human–environment dynamics, as revealed by archaeological and palaeoecological study, provides insights into the relative impact of humans on pristine island ecosystems, the influence of environment on ecosystem vulnerability, and the ways in which societies have modified their economies, sociopolitical structures, and other aspects of culture in response to long-term environmental changes.