The boundary layer effect in rectangular laminated plates is studied using an efficient third order zigzag theory. For this purpose, a Levy-type solution is presented for rectangular plates, with two opposite edges hard-simply supported. A mixed formulation is employed for the solution. The numerical results are presented for composite and sandwich plates with four boundary conditions. While strong edge effects are observed at the free edges and soft-simply supported edges, no edge effect appears at the hard-simply supported edge. The effect of length to thickness ratio and aspect ratio on the boundary layer is investigated. The results are compared with those of the smeared third order theory to ascertain the effect of inclusion of layerwise terms in the displacement approximation of the zigzag theory.