Using a C 0 eight-noded plate element developed based on an accurate higher-order theory, the nonlinear dynamics analysis of thick composite and sandwich plates are investigated. The formulation is based on a theory that accounts for the realistic variation of in-plane and transverse displacements through the thickness. It also includes the inertia terms pertaining to the higher-order terms involved in the displacement functions. The geometric nonlinearity is introduced in the formulation based on the relevant Green's strain vector for the laminate. The governing equations of motion obtained here are solved through eigenvalue solution for free vibration case whereas the direct integration technique is employed for the transient response analysis. The performance and the applicability of the proposed discrete model for the nonlinear free flexural and forced vibration responses of thick laminates are discussed among alternate models, considering multi-layered cross- and angle-ply, and sandwich plates.