Oxygen isotope analyses of corals from the Gulf of California and Gulf of Panama are calibrated with environmental parameters. Uncertainty in the isotopic composition of sea water in the Gulf of California prohibits strong correlation between temperature and δ\sp18O. The marginal condition for coral growth in the Gulf of California prevents the construction of a long paleoclimate record. The Gulf of Panama record is strongly correlated with salinity (r\sp2 = 0.72) and indicates a trend toward drier conditions in Panama since 1950. Although El Nino is recorded in both records through a decrease in the annual maximum isotopic value, this signature is not unique to El Nino thereby minimizing the ability of corals to monitor this system. Strong coherence between the Gulf of Panama record and three other Panamanian records attests to the ability of corals to record regional climate variability.