A finite-element model is presented for studying the buckling and postbuckling behavior of composite laminates with an embedded delamination. Degenerated-shell elements and rigid-beam elements are utilized for the finite-element model. In the non-linear finite-element formulation, the updated Lagrangian description method based on the second Piola-Kirchhoff stress tensor and the Green strain tensor has been used. The buckling and postbuckling behavior are investigated for various delamination sizes and boundary conditions. Three different possible modes of instability are identified at the critical lend, i.e. global, mixed, and local buckling modes. It is shown that the buckling load and postbuckling behavior depend on the buckling mode, which is determined by the delamination size and boundary conditions. It is also found that bifurcation buckling occurs for composite laminates with an embedded delamination. (C) 1997 Elsevier Science Limited.