A general one-dimensional (1D) model of composite delaminated beams with deformation effect is derived for buckling behavior. The constitutive models of composite laminated beams are derived from the classical 2D laminate theory. The present cylindrical bending models can be used--with much greater accuracy than their well-known plane-strain and plane-stress counterparts--as upper and lower bounds toward one of which the behavior tends, depending on the width-to-length ratio. The analysis is based on the first-order Timoshenko-Mindlin kinematic approach. The differential equations are solved with the aid of a specially developed, very efficient interlaced finite-difference scheme eliminating the shear locking phenomenon. A parametric study of the deformation effect associated with various constitutive models is carried out for angle-ply delaminated laminate. It was found that the most significant difference between the models is associated with the mix of local and global modes.