There has been an explosion of interest in cluster analysis since 1960. The "explosion" of this literature is documented through: (a) a rapid growth in the number of articles which have been published using this technique; (b) the wide range of sciences interested in clustering; (c) the large and growing number of software programs for performing cluster analysis; (d) the formation of cliques of cluster analysis users; and (e) the resulting fragmentation of terminology into jargon which restricts interdisciplinary communication. In response to the effects of this explosion, it is expected that the future literature on clustering will contain a number of attempts at consolidation. Nevertheless, the facts that cluster analysis has no scientific home, that clustering methods are not based upon a well-enunciated statistical theory and that cluster analysis is tied to the complex topic of classification means that the consolidation of this literature will be difficult.