A brief review is given of the evolution of our ideas on the mechanism of catalytic reforming reactions over the last 40 years. The early bifunctional reaction mechanism, though criticized much, led first to an understanding and optimization of the reforming process and later to several other catalyst and process innovations. Kinetic and tracer studies on model catalysts using single hydrocarbons as reactants and the surface-science approach revealed the finer nuances of the mechanism involved. Simultaneously, the roles of S, Cl, coke, and hydrogen and of a second metal component like Re, Ir, or Sn in the industrial catalyst were also understood to a greater or lesser extent. All these results make the mechanism of reforming reactions a field of fascinating complexity in fundamental and industrial catalysis.