ESDU 72012 gives general information on the data in the Structures Series on quadrilateral plates and panels subjected to in-plane compression. It covers behaviour at initial buckling@ immediately after buckling and at failure in local or overall modes. A plate is defined as a portion of sheet bounded by longitudinal and transverse members or a portion of sheet bounded by two or three such members and having the remaining one or two sides free. A panel is defined as a sheet bounded transversely by sturdy frames between which the sheet is stiffened by longitudinal members (stringers). For a panel the major compressive stress is taken to be acting parallel to the stringers. The stringers and frames may be integrally manufactured with the sheet or separately attached.