During the past three decades since the publication of the last volume on the magnetic susceptibilities of co-ordination and organometallic transition metal compounds thousands of new paramagnetic compounds of striking diversity and novelty have appeared. The present volume on the magnetic properties of paramagnetic compounds covers 1663 references published between 1985 and 1991. After an introduction into the theoretical aspects of the paramagnetic susceptibility, the data tables are providing experimental values for susceptibility, effective paramagnetic moment, and paramagnetic Curie constant. Where available the tempereature dependence of the magnetic susceptibility is given in figures. The compounds are listed under their central metal ion (transition metal, lanthanide or actinide) of definite, or mixed, oxidation state. The substances include simple compounds, co-ordination compounds (N-ligands, O-ligands, S-ligands, etc.), organometallic compounds, homo- and hetero-multimetallic derivatives, clusters, polymers. Finally, data for organic radicals are given.