Laboratory experiments have indicated that waves have a noticeable influence on the value of the drag coefficient. On the basis of data from our laboratory and others as well as field studies, we conclude that for a developing wave field under neutral stablility conditions the roughness length formula proposed by Kitaigorodskii (1970) offers a reasonable parameterization of the roughness length and the drag coefficient under a variety of wind and wave conditions. Additionally, it is shown that the Kitaigorodskii formula is a generalization for both the Charnock (1955) and Hsu (1974) formulae. The results of this study also offer an explanation for the scatter in the previous studies of drag coefficient as a function of wind speed alone.