Diffraction from totally relaxed, partially relaxed, and unrelaxed strained‐layer superlattices is considered in the light of the similar rocking curves obtained by convergent‐beam electron diffraction and x‐ray diffraction. Diffraction of the superlattice can be described by an intensity expression given in terms of the strains and thicknesses of the superlattice bilayer. It is shown that the intensity profile of a reflection of a given superlattice depends on the difference of the tensile and compressive strains, i.e., the oscillating strain, of the superlattice bilayer. The oscillating strain of the superlattice bilayer, to a very good approximation, is independent of the state of strain in the step model of the superlattice. The insight gained leads to the understanding and prediction of the general form of the rocking curve of a superlattice from its growth parameters, although simulation of the rocking curve is still needed in order to obtain accurate structural parameters.