Orientations of the OH-vectors of the structural OH-groups of layered silicates have been determined from diffraction data and from calculations of electrostatic energy. A comparison of the results from both methods has shown that in the hydroxyls of the 2:1 layers of micas and chlorites, the position of the hydroxyl proton is mainly determined by electrostatics. In the case of the internal hydroxyls of dickite and those of the brucite lattice of the chlorites, the results derived from these two methods differ constantly, indicating a change in the nature of the bond in these hydroxyl groups. -D.A.B.