Combinatorial and high-speed screening techniques, which have revolutionized the search for new drug molecules, are now finding broader application in the chemical and materials development areas. The ability to generate large "libraries" of samples and to evaluate their performance simultaneously reduces the time and cost per sample and enables multicomponent parameter spaces to be explored. In the area of catalyst development, the impact of this technology promises to be substantial, not only in synthesis and performance evaluation, but also for the optimization of operating parameters. In this review, the major experimental approaches are described; for heterogeneous catalysts, especially, the parallel approach proves the most useful, rather than the "split-and-mix" methods of drug screening. Novel techniques for the high-speed, parallel performance evaluation of catalyst arrays are reviewed with numerous recent examples. Indications are provided of expected future trends in this rapidly developing area.