The intent of this chapter is to give the first elements for the comprehension of the mechanism of inorganic reactions in solution. The coverage is necessarily restricted to some mechanistic aspects of transition metal coordination (Werner type) compounds that are considered essential. The initial part deals with the acquisition of the experimental data, the recognition of the rate law and the mechanistic classification. A survey of ligand substitution reactions on four- and six-coordinate metal centers followswhich includes the exchange at a metal center between coordinated and bulk solvent molecules and the influence of labilization effects caused by ancillary ligands, metalcarbon bonds, basic ligands, etc.. Factors controlling the lability or the inertness of complexes are shortly discussed. Finally, the focus is shifted to the mechanism of electron-transfer reactions and to the dynamic behavior of the ligands.