The events leading to the current study of the mechanism of surface reactions on metals are discussed. This article is written with graduate students in mind, with particular attention on the aspects of the development of surface science that lead to significant advances in the capacity to understand complex reactions of organic substrates adsorbed on solid surfaces. The field is traced from the advent of the postacceleration low energy electron diffraction through the methods used to unravel the mechanism of complex surface reactions used today. It is a personal account of the course of surface science and the hallmark developments in the field that affected my research most significantly. Examples are given that trace the development of studies of the mechanism of surface reactions over the last three decades.