The Provincelands in the Cape Cod National Seashore developed about 5 ka from wind- and waterborne Outer Cape Cod outwash sands as sea level rose to submerge offshore banks. A late Holocene chronology of sand dunes in the Provincelands is established from radiocarbon-age determinations on the basal organics from interdunal bogs and ponds. The Provincelands ponds, thought to be lakes trapped behind hooked spits, are shown here to have developed from bogs similar to those in the extant parabolic-dune field. An older, stabilized dune field in the location of the ponds is hypothesized. Episodes of alternating dune movement and interdunal-wetland formation in the Provincelands correlate with climatic changes in the North Atlantic and elsewhere during the last 1.2 ka, as interpreted from ice core, glacier movement, sea-surface temperature, tree-ring, pollen, and historical data. The dune field data suggest a periodicity of change of 0.2 ka. Before about 1.2 ka, dunes in the Provincelands were active. Between about 1.15 and 0.9 ka, bogs formed which, at least in the west-central area of the Provincelands, developed into ponds having continuous organic sedimentation until today. This evidence indicates that the west-central dune field stabilized after 1.1 ka. Between 0.9 and 0.7 ka, dunes were active in the north and east-central Provincelands, but from about 0.7 to 0.5 ka, bogs formed within that dune field, and at least one bog in the west-central area became a pond, both events indicating a warm and wet climate. During the Little Ice Age (0.5 to ∼0.2-0.1 ka), the Provincelands dunes were active, suggesting a cold, windy, and dry climate. Because of a warmer and wetter climate during the last 0.1 ka, bogs have formed again within the dunes.