Self‐consistent spin‐polarized energy‐band calculations are reported for theRCo2compounds (R=Tb–Yb). By changing the magnitude of the 4fspin in GdCo2from zero to seven and back to zero, hysteresis was obtained with both low‐ and high‐moment conduction‐electron states being obtained for spin less than 4. For the real compounds, when the calculations were started with no moment on the Co, low‐conduction‐electron moments were obtained for DyCo2–YbCo2. However, when the calculations were started with large moments on the Co the total conduction‐electron moments were calculated to be 1.75 &mgr;B/f.u. for all of the compounds. It is suggested that the conduction‐electron‐state densities in all of the compounds are similar to those in YCo2and LuCo2and that the conduction‐band system is essentially metamagnetic.