In 1988, Fairbanks conducted a drilling expedition off the south coast of Barbados to recover submerged corals contemporaneous with the last deglaciation. Core recovery was excellent and >30 different samples were dated by conventional β-counting techniques (Fairbanks 1989). At about the same time, we developed, at Lamont, the thermal ionization mass spectrometry (TIMS) technique to obtain precise U-Th ages (Edwards 1988), and to compare them with the14C estimates measured on the same samples. A surprising result was that the discrepancy between14C and U-Th ages increased through time toca.3000–3500 yr atca.15,00014C BP (Bardet al.1990a). Because the three youngest samples yielded U-Th ages in agreement with their calibrated14C ages, we concluded initially that the TIMS U-Th determinations were not only precise, but also accurate, and that the14Cvs.U-Th data set could be used for a first-order14C calibration.