Although the optical spectra of LnCl(6)(3-) systems are complex, only two crystal field parameters, B-40 and B-60, are required to model the J-multiplet crystal field splittings in octahedral symmetry. It is found that these parameters exhibit R and R-7 dependence, respectively, upon the ionic radius Ln(3+)(VI),but not upon the Ln-Cl distance. More generally, the crystal field strengths of LnX(6) systems (X = Br, Cl, F, O) exhibit linear relationships with ligand electronegativity, charge transfer energy, and fractional ionic character of the Ln X bond.