A simple x‐ray diffraction method was used to measure the mosaic misalignment and the number of dislocations in the grains of silver halide precipitates and of nickel foils where the grain sizes were in the range from a few tenths of a micron to a few microns. The experimental arrangement is such that separate diffraction spots are produced by each grain and the width of a spot is determined primarily by the mosaic nature of the grain.It appears that measurements of angular misalignment can be made down to the limit imposed by the natural width of the x‐ray spectrum lines. In general, either cold work or the presence of a substitutional impurity causes broadening of the diffraction spots. However, it is possible to incorporate impurities without producing broadening or dislocations. In spite of a 1% substitution of iodide impurity in silver bromide, grains were produced which appear to have no edge dislocations.