Frames made up of rectangular elements are usually statically indeterminate, i.e. the stresses in them can be found only by taking into account the relative stiffness and deformation of the various members. The common use of rectangular frames in engineering structures makes it highly desirable that the most convenient methods of analyzing their stresses should be developed. The stresses in a number of such rectangular frames have been analyzed in this research, and this report describes the methods used and presents the formulas derived.