Governing equations are derived for the response of partially ice-covered continental shelf waters to atmospheric and tidal forcing. The assumptions underlying these equations are discussed, with emphasis on the physical processes represented by the air-ice and ice-water drag coefficients. Combining the equations that separately govern the water and ice floe motions, a coupled ice-water equation is obtained. The coupled equation reduces, under certain simplifying assumptions, to an equation involving only the air and water velocities relative to the ice velocity. This suggests an approximate but extremely simple methodology for the determination of drag coefficients for ice floes. The methodology is applied to data obtained during BASICS and MIZEX, and shown, in the former application, to yield drag coefficients comparable to those obtained from considerably more laborious methods.