The paramagnetic resonance spectrum of divalent manganese has been measured in a single crystal of CdSe (C6v4) at 77°K. The parameters are g=2.003±0.001, A=(-62.7±0.5)×10-4 cm-1, D=(15.2±0.5) ×10-4 cm-1, a=(+14.3±1.0)×10-4 cm-1, F=(-2.0±1.0) ×10-4 cm-1. It is to be noted that in this hexagonal crystal the effect of the cubic field parameter a is comparable to that of the axial field parameter D. The large value of a is attributed to covalency effects. A comparison of the measured a value with a values found for Mn++ in other wurtzite and zincblende crystals shows that there is a correlation between the magnitude of the a value and the amount of covalency. A similar correlation between the value of D and the amount of covalency is also found and accounts for the low value of D in CdSe. © 1963 The American Physical Society.