In this work, we report and analyze the results of a cycle of the neutron investigations of a number of rare� earth compounds based on SmB6 , SmS, and YbB 12 . These systems are usually classified as Kondo insula� tors (1) (for the case of SmS, at a pressure of higher than 0.6 GPa) with various valence instability degrees of a rareearth ion. This degree is sufficiently high for SmB6 and its derivatives, varies in a wide range for "chemically compressed" Sm(Y)S (simulating the intermediatevalence state of SmS under compres� sion), and is slightly different from an integer for YbB12, as in heavyfermion systems. All of these com� pounds are characterized by the presence of a gap (or pseudogap) in the electron density of states near the Fermi energy and the nonmagnetic ground state, which are formed due to strong electron correlations at temperatures below a certain characteristic value of about several tens of Kelvin. In the diverse neutron experiments, the energy structure of the magneticexcitation spectrum, the characteristic features of the momentum dependence of the energy (dispersion relation), and the intensities of these excitations have been determined. The tem� perature dependence of the spectral function and the effect of the introduction of the defects into the mag� netic sublattice, i.e., the role of the cooperative effects on the formation of the ground state have been ana� lyzed. Specific excitations have been revealed in the energy range of 10-20 meV; the main properties of these excitations are similar to those of the socalled "resonance" mode, which is studied and actively dis� cussed in works devoted to the hightemperature superconductor cuprates (see (2, 3) and references therein).