A study of the sensitivity of the simulated Asian summer monsoon to changes in general circulation model formulation is reported. The baseline version of the model fails to realistically simulate the precipitation, wind, and temperature fields. In one experiment the stratiform cloud parameterization was changed from a simple large-scale saturation scheme to a scheme that prognostically determines cloud water, cloud ice, and rain. In a second experiment a parameter that relates the cumulus mass flux to the cumulus kinetic energy was altered so as to increase the convective adjustment time. These changes in the stratiform and cumuliform cloud parameterizations significantly improve the simulations of the precipitation and upper level wind fields, respectively. ¿ 1999 American Geophysical Union