A simple, analytic expansion about the critical point appears capable of adequate representation for the compression factor in the single phase region near the critical point. The equation requires T-c, P-c, V-c, and omega to predict the compression factor, and we have used it to represent the behavior of argon, carbon dioxide, ethene, methane, and nitrogen. The scaling hypothesis would indicate that this expansion is invalid; however, the best available data seem to be susceptible of such treatment. The equation can also represent phase behavior in the critical region by utilizing it with the Maxwell criterion.