It is shown that the ESR modes observed in Cu: Mn alloys can be explained in terms of an Edwards-Anderson-type theory for a spin-glass when an anisotropy energy is included. Unlike other theories, the present one involves the conventional form for this anisotropy, ${U}_{K}=K{sin}^{2}\ensuremath{\theta}$, where $\ensuremath{\theta}$ is the angle the local microscopic magnetization makes with the symmetry rather than equilibrium direction. The present theory is distinguished by a predicted, but as yet unobserved, angular dependence of single-crystal samples with axial symmetry.