This paper presents a summary of the experimental and analytical research on flat plates under concentrated normal loads conducted at the Aluminum Research Laboratories. The experimental work includes tests on a number of different sizes of plates, ranging from 1/8 in. to 1 in. thickness, loaded on spans of from 48 to 384 times the thickness. The effect of the degree of load concentration, types of edge support, and position of the load upon the stresses and deflections have been the principal variables studied. Cases of bending alone, and combined bending and direct stress have been considered. The analytical work refers to the existing general analysis of the flat-plate problem, from which formulas suitable for design purposes have been derived.