The dependence of ocean normalized radar cross section (NRCS or &sgr;0) on the 19.5 m neutral stability wind vector for the SEASAT-A Satellite Scatterometer (SASS) is described. For the SASS wind vector algorithm this dependence is specified in the form NRCS = f(ϑ, &khgr;, U), where ϑ is the radar incidence angle, &khgr; is the angle between wind direction and radar azimuth, and U is the neutral stability wind speed in meters per second at a height of 19.5 m. The development of models to express this relationship and to provide the basis of inversion of NRCS to SASS winds is traced from its initial form based on aircraft scatterometer measurements through the SEASAT fields-validation experiments (GOASEX, STORMS, and JASIN) to its final form. Comparison of the model NRCS versus surface wind speed with SASS data from these experiments are made.