The dependence of the ferromagnetic resonance upon specimen anisotropies (shape and magnetocrystalline) is well known. Observations of the ferromagnetic resonance absorption of submicroscopic particles may be interpreted to yield useful information about these anisotropies. The alloy 2% Co&sngbnd;Cu heat treated to precipitate cobalt containing about ten percent copper from the nonmagnetic solid solution has been studied using ferromagnetic resonance techniques. In the early stages of growth the precipitate particles are shown to be essentially spherical in shape. Further growth of the precipitate particles (by subsequent heat treatment) is accompanied by aspherical shape changes which modify the resonance spectra. The magnetocrystalline anisotropy of the cobalt precipitate in single crystals of this alloy has been determined. This anisotropy is cubic withK1/Ms=−665 oe at room temperature. The cobalt‐rich precipitate retains its cubic crystal structure to at least 4.2°K, apparently stabilized by the copper matrix.