A 500-kyr paleoceanographic record from the mid-Pleistocene Transition (MPT) is documented from ODP Site 1125. The chronological framework is based on carbonate reflection correlation with orbitally tuned Site 1123 nearby. Site 1123 contains two tephra layers (0.92, 0.83 Ma), which provide a reliable age correlation with Site 1125. Two biostratigraphic events (0.95, 0.85 Ma) as well as the coiling ratio record of Truncorotalia truncatulinoides were also used to develop the age model. Lithologic parameters, together with planktic foraminiferal census data at Site 1125, display glacial-interglacial contrasts that are reflected in the carbonate reflection measurements and sea surface temperature (SST) estimates. Modern Analogue Technique (MAT) and Transfer Function SST estimates, based on planktic foraminiferal census data, show that the average interglacial summer SSTs were similar to modern values (18 degrees C). After marine isotope stage (MIS) 27, the glacial-interglacial amplitude increased some 2-4 degrees C and culminated in a 6 degrees C drop in summer SSTs at MIS 16. This is similar to Last Glacial Maximum (LGM) values. A trend of increasing severity of glacial temperatures at Site 1125 coincides with the global MPT trend, but is not paralleled by increasingly warm interglacials. (auth/DG)