The computation of Λ-doublet splittings in diatomic 2Π electronic states has become almost routine with accuracies of 1% obtainable for light hydrides. The spin−doubling which occurs in 2Σ states has received less attention: the only example seriously studied is HF+. Here this work is extended to CaH. Apart from the effects introduced by incorporating a third-row atom, CaH is of intrinsic value as its spectrum is of importance in resolving the puzzle of the apparent depletion of Ca in the interstellar medium relative to its abundance in stars.