Combined geological and archaeological data sets indicate that sea level–controlled topography best explains the timing of Neolithic settlement onto the southern Yangtze delta plain, almost 1500 yr later than inland China. Information on settlement patterns of the three major Neolithic cultures (Ma-Jia-Bang, Song-Ze, Liang-Zhu), dated from ca. 5500 to 2200 B.C., is provided by petrologic study of habitat bases of sites and of sediment cores recovered near the sites. In the early Holocene, rising sea level induced decreased relief and an aggrading silt mantle on the low-lying delta surface. Changes of sea level and climate from early to mid-Holocene initiated a fertile delta plain at ca. 6000–5500 B.C., and settlement and cultivation, including rice, began within only 500 yr of delta formation. Rate of sea-level rise decelerated by mid-Holocene time, resulting in rising ground-water level and poor drainage, and a reduced delta plain area suitable for human occupation and agriculture. As a consequence, Neolithic settlements shifted progressively eastward toward higher, more restricted areas of the Yangtze delta chenier plain.