Tropical ocean modeling has played a major part in the development of our knowledge of El Ni¿o-Southern Oscillation (ENSO) during the Tropical Ocean-Global Atmosphere (TOGA) decade. Although the foundations had already been laid, it was only with the impetus from TOGA that tropical ocean modeling was able to develop so extensively. In this paper we discuss the development of the wide range of tropical ocean models in use today, from the simple to the complex; the ways in which their abilities to reproduce different phenomena have been assessed; and the ways in which they are being used to better understand and predict the behavior of the coupled ocean-atmosphere system in the tropics. Ocean model development is far from finished, however. Outstanding issues such as forcing fields, model improvements, testing strategies, and applications are also discussed. There is at least as much work to be done in the next decade as was achieved in the last. ¿ 1998 American Geophysical Union