While the history of catalysis goes back to antiquity, catalysis as we know it today began in the nineteenth century with catalytic hydrogenation having its beginning with the report by Sabatier in 1897 on the hydrogenation of ethylene over a reduced NiO catalyst. The ground-work for future study of catalysis was laid in the early twentieth century primarily by what we would call today Physical Chemists. About the middle of the last century, though, catalysis, particularly catalytic hydrogenations and oxidations, began to be used more extensively in synthetic applications. With the primary interest being selectivity, these reactions became part of the synthetic chemist's 'tool box'. The last quarter of the past century saw an increased interest in understanding the details of the chemistry taking place on the catalyst surface. Surface Science techniques were used to define the nature of the active sites responsible for promoting specific reactions. EHMO calculations provided information on the nature of the interaction between the substrate and metal catalyst surface. This approach was recently replaced by the use of DFT calculations to obtain information on the energetics of the interaction of a metal surface and the substrate or presumed reaction intermediates. Another twenty-first century innovation was the introduction of "nano-technology" with nano-particles of metals being used as catalysts. Thirty years ago these were referred to as dispersed supported metal catalysts. The question is, then, with this introduction of new experimental and computational techniques, has the central goal of catalysis, efficient and selective synthetic capability and pollution abatement, been overshadowed by the very nature of the experimentation being used? Has the research leading to a more detailed understanding of the catalyst surface led to the preparation of more active and selective catalysts or are the better catalysts still being prepared by the old trial and error approach? Perhaps more efficient catalysts could be designed if there were a better understanding of what was taking place on the surface of 'real world' catalysts rather than on idealized substitutes. The presentation will cover a brief review of catalysis with emphasis on catalytic hydrogenation including proposals about the nature of catalytic active sites which were made through the years. Some suggestions will be made as well as the identification of some apparent contradictions. Finally, a few areas of potential future research interest will be mentioned. [GRAPHICS] .