The magnetic and crystallographic properties of rare-earth cadmium compounds of equiatomic composition were studied. All compounds were found to be ferromagnetic. Indications were obtained that the CsCl structure type is not stable at all temperatures. The magnetic properties of the rare-earth cadmium compounds are compared with the isostructural zinc and magnesium compounds. It is suggested that, apart from the RKKY interaction involving s -conduction electrons, there exists a second coupling mechanism which in some cases even predominates.