Saturation magnetization and neutron diffraction measurements have been performed on cubic Laves phase compounds RCo2 in which R is Nd, Tb, Ho, and Er. Neutron powder patterns obtained at room temperature and at 15°K allowed the determination of the magnetic structures. The low‐temperature patterns are of the ferromagnetic or ferrimagnetic type, with large magnetic intensities superimposed on the nuclear peaks. For the compounds of Tb, Ho, and Er, the rare‐earth atoms show nearly the full moment expected for the free tripositive ion and the cobalt moment is about one Bohr magneton. The rare‐earth moments are coupled parallel to each other, but antiparallel to all the cobalt moments. For NdCo2, the observed Nd moment of 2.6±0.2 Bohr magnetons is smaller than the free ion value of 3.27 Bohr magnetons, and it is coupled parallel to the cobalt moment of 0.8±0.2 Bohr magnetons. In the Nd ion, the spin is opposite to the moment (J = L−S), while for the heavier rare earths the spin is parallel to the total moment (J = L+S). Thus, in all cases there is antiparallel coupling between the spins of the rare‐earth and cobalt atoms. The values for the total moment per molecule based on the neutron diffraction results are in satisfactory agreement with the magnetization measurements.