We apply spin-noise spectroscopy to the classical objects of electron paramagnetic resonance spectroscopy—dielectrics with paramagnetic impurities—which seemed to be unsuitable for this technique because of their low specific Faraday rotation (FR) associated with strong (allowed) optical transitions. We show, however, that by detecting the spin noise at the wavelengths of weak (forbidden) transitions (with low regular FR), the signal can be strongly enhanced, provided that the optical transition is broadened inhomogeneously. This spin-noise gain effect, which is controlled by the ratio of the inhomogeneous linewidth to the homogeneous one, relates primarily to the parity-forbidden intraconfigurational transitions of the impurity ions with unfilled inner electronic shells. Specifically, for the
f
−
f
transitions of rare-earth ions in crystals, this factor can reach
∼
10
8
. In this paper, we describe the specific features of the experimental equipment required for the realization of this kind of measurements, present results of successful experiments of spin-noise spectroscopy on rare-earth ions in crystals, and briefly discuss the prospect of applying this method of magnetic resonance spectroscopy in present-day research.