Ten years after the Ocean Drilling Program (ODP) Leg 119 in Prydz Bay, a new phase of ODP Antarctic margin drilling started in 1998 with Leg 178, on the Pacific margin of the Antarctic Peninsula. Drilling sampled three geological environments of the continental margin where a record of the onset of glaciation and periodic expansion of the ice sheet to the continental shelf edge would be preserved. Leg 178 drilled at: (1) three sites (1095, 1096, 1101) in sediment drifts on the continental rise, which retain an indirect but continuous and expanded record; (2) four sites (1097, 1100, 1102, 1103) on the outer continental shelf, which retains a direct record, though discontinuous and difficult to recover; and (3) two sites (1098, 1099) in the glacially overdeepened inner shelf basins, natural sediment traps that contain an ultra-high-resolution record of the Holocene. Shelf drilling did not extend back to the onset of glaciation, but showed the glacial nature of Sequence S3 (early Pliocene and older). Rise drift deposition was sensitive to regular grounded ice advance to the shelf edge back at least to 9 Ma, including throughout the "warm Pliocene". Leg 178 has provided the first estimates of the timing and evolution of the ice sheet covering the Antarctic Peninsula, an area very sensitive to climatic change but with a different glaciological character from the rest of the continent. More importantly, it has validated in the field a new approach to reconstruction of Antarctic Cenozoic glacial history, and opened the way to the next phase of Antarctic ODP drilling.