Thermochronologic studies of high P, low T metamorphic rocks provide constraints on protolith ages, subduction burial rates, the timing of subduction related metamorphism, and the timing of subsequent exhumation. Temperature-time data is essential for reconstruction of accurate P-T-t paths, unambiguous interpretation of the tectonic significance of P-T paths, and to test thermal models which predict the time scales required for the preservation of high P, low T assemblages. The P-T-t histories of high P metamoiphic rocks from the western Baja terrane and the Aegean are used as examples to illustrate how thermochronologic data can be used to gain insight into forearc processes. Differences in exhumation rates and the degree to which high P, low T metamorphic rocks are overprinted reflect the variability in processes affecting convergent margins. Steady-state subduction characterized by low geothermal gradients in western Baja enables slow blueschist exhumation to occur without overprinting of high P, low T mineral assemblages. In contrast, subduction followed by back arc extension in the Aegean requires rapid exhumation of high P metamoiphic rocks to prevent overprinting by higher temperature mineral assemblages during subsequent higher T metamorphic events. P-T-t and structural data in other areas (e.g., Papua New Guinea, New Caledonia) indicate extension tectonics has played a key role in the exhumation of high P metamorphic rocks.