Fisson-track thermochronologic studies on mid-Cretaceous diortic and tonalitic rocks from Tobago, West Indies, provide important temporal constraints, on post magmatic Mesozoic cooling as well as the final phase of accretion of these oceanic-arc plutonic rocks onto the continental margin of northern South America. Zircon fission track data indicate that the plutonic rocks of Tobago cooled through the zircon closure isotherm (250-200 ¿C) at about 103 Ma. Apatite ages and track length analysis suggest rapid cooling through the apatite annealing zone (120¿-60 ¿C) at a bout 45 Ma. Furthermore, the track lengths in apatites from these plutonic rocks are all greater than 14 microns, which implies that these rocks have not been avove 50 ¿C since 45 Ma. If a geothermal gradient of 25 ¿C/km is inferred, the analyzed samples have been at depths of less than 2 km since 45 Ma. Tobago has occupied an upper crustal structural position since the mid-Cretaceous, and significant final uplift of these Mesozoic oceanic-arc rocks occurred in the mid-Eocene. The tectonthermal history of Tobago since the mid-Eocene has not involved deep burial or a high-temperature thermal flux. This history apparently has chiefly involved translation of the Tobago terrane along the Caribbean-South America Plate Boundary Zone at upper crustal levels. ¿ American Geophysical Union 1993