Concurrent tandem catalysis (CTC) involves the cooperative action of two or more catalytic cycles in a single reactor. In CTC, each catalyst must be compatible with substrates, intermediates and other catalysts and must also exhibit reaction sequence selectivity. This review describes, in general terms, published CTC reaction schemes that have been reported through May 2004. First, a simple classification scheme for coupled catalytic cycles is proposed. Following this, specific examples, grouped by reaction classes, is presented with emphasis placed on methodologies utilized for the development of CTC. Finally, future prospects including developmental approaches related to tandem catalysis are outlined.