Among cluster compounds of boron, the metallacarbaboranes form a well‐established family that has developed significantly over the last decade, for example, with regard to
f
‐block‐containing species and supramolecular systems. This article covers the basic principles of metallacarbaborane clusters: classification of clusters, structural, and bonding aspects. An attempt has been made to illustrate synthetic routes to metallacarbaboranes in a systematic manner, although it must be recognized that many other syntheses reported in the literature lack a strategic quality. Isomerism of the cluster skeleton is discussed with pertinent examples. Electrochemical properties of cluster and stacked metallacarbaboranes are summarized. An overview of typical patterns in reactivity is given, although, as with synthetic strategies, it is extremely difficult to generalize. Potential applications of metallacarboranes are covered in this article, but the discussion is selective in view of recent review articles.