Twenty years ago Tanabe and Sugano published the first ligand field energy diagrarns which are applicable to dN electronic configurations. These diagrams are limited in scope in that they can be used only for octahedral symmetry and for a limited number of terms. The present volume is an attempt to fill the gap by providing a reasonable nurober of complete and accurate ligand field energy diagrarns for dN configurations in the most commonly encountered symmetries. Despite their limited nature, the diagrarns of Tanabe and Sugano were exten­ sively used in the past in order to rationalize optical and luminescence spectra and to discuss various electronic properties of transition metal ions, their coordination compounds and solids. Moreover, Tanabe-Sugano diagrams have an established place in the theory of transition metal compounds and are included in most textbooks of inorganic and coordination chemistry. It is expected that the present diagrarns will be found useful for a similar purpose.