Section A: Quantum Chemical Foundation. Theoretical foundation of quantum molecular similarity; R. Carbo, E. Besalu. Molecular similarity and momentum space; D.L. Cooper, N.L. Allan. Molecular similarity measures for assessing reactivity; P.G. Mezey. Electron density approximations for the rapid evaluation of quantum molecular similarity measures; J. Mestres, M. Sola, E. Besalu, M. Duran, R. Carbo. Section B: Computational Methods. General suggestions and applications of quantum molecular similarity measures from ab initio fitted electron densities; J. Mestres, M. Sola, M. Duran, R. Carbo. Quantitative measurement of molecular similarity using shape descriptors; R.P. Bywater. PROTEP: a program for graph-theoretical similarity searching of the 3-D structures in the proterin data bank; P.J. Artymiuk, H.M. Grindley, A.B. MacKenzie, D.W. Rice, E.C. Ujah, P. Willett. 3-D Molecular similarity modelling in computational drug design; D.C. Rohrer. Application of adaptative mixture of local neural networks in chemistry. Prediction and classification of resonance and inductive effects of substituents; V. Kvasnicka. Section C: Phenomenological Approaches. Similarity and analogy in chemistry; D. Rouvray. Graph theoretical approach to structural changes in chemistry; J.-E. Dubois, G. Sicouri. Detection of the largest patterns common to a set of molecules, using 2D graphs and 3D skeletons; D.M. Bayada, A.P. Johnson. A proposal towards the identification of substructure electronic similarity; B. Leoni, G. Sello. Study of the root mean square deviations of bond lengths, bond angles and torsional angles as a measure of molecular similarities; N.J. Smeyers, Y.G. Smeyers.Molecular similarity and LFER; R. Ponec. Evaluation of molecular similarity using topological fragment spectra; Y. Takahashi, Y. Ishiyama. Index.