In 1972, Edward N. Adams III published what might be the first paper on consensus techniques for use in biological classification. He addressed the following question: ‘… can we combine the information from rival classifications into a new, hopefully more accurate classification? Such a consensus of the rivals is useful both in tree comparison and tree discovery’ (Adams 1972, p. 390). Since Adams’ paper, nearly half a century ago, numerous consensus tree techniques have been proposed, numerous critiques of each have been published and an almost infinite number of suggestions have been made as to how to use one of them, some of them, any of them, all of them, or none of them (Bininda-Emonds 2004a, 2004b). Alongside this avalanche of technical detail are discussions concerning supertrees (which are a form of consensus analysis) and supermatrices, the latter being an extension of the ‘combining data’ debate (Sanderson et al. 1998, see the following Chapter 10). Again, as with the methods of data analysis described in Chapter 8, we do not intend to discuss each and every consensus technique in detail but deal with what we understand to be the basic issues (on the details of consensus methods, we make some suggestions in the Further Reading section below).