This paper is concerned with the numerical accuracy of a predictor-corrector form of the Crank-Nicolson Scheme for solving boundary layer equations. According to Blottner, the Crank-Nicolson Scheme, with a predictor-corrector step to deal with nonlinearity, exhibits only first-order accuracy unless the boundary layer continuity and momentum equations are solved in a coupled manner. In the present paper, a predictor-corrector form of the Crank-Nicolson Scheme, based on a coupled solution for the continuity and the momentum equations, is presented for both the incompressible and compressible flows. The present scheme is then subjected to a computer experiment using the problem of the laminar boundary layer development in a linearly retarded edge velocity field. The results are then compared with the Davis Coupled Scheme. It is shown that the present scheme posesses second-order accuracy and is more efficient than the Davis Coupled Scheme.