The time interval represented by marine isotope stages (MIS) 11 and 12 (ca. 360–470 ka) may contain the most extreme glacial and interglacial climate conditions of the late Pleistocene. Sediments from the Bermuda Rise (western North Atlantic) provide clues to the nature of climate variability during this period. Our geochemical records indicate that millennial-scale climate instability and associated changes in North Atlantic Deep Water (NADW) production occurred during both interglacial MIS 11 and glacial MIS 12. Stage 12 is punctuated by a series of interstadial events that occurred at a 5–6 k.y. periodicity, and the occurrence of ice-rafted debris at various times during stage 12 indicates that icebergs were present at least as far south as 34°N during this glacial period. Within the limits of our correlation, the atmospheric temperature changes recently reported for the Vostok ice core for the stage 11 time period appear to be represented by coeval changes in NADW flow. Specifically, warming in Antarctica is associated with increased production of NADW.