Since the first application of dendrimers in catalysis in the mid 1990s, this field has advanced rapidly. As a consequence, catalytically active dendrimers have emerged as a class of molecular catalysts that has substantially enriched the field of homogeneous (and in part heterogeneous) catalysis. A general survey of transition metal dendrimer catalysts and the way they have developed is followed by in-depth discussions of dendritic transition metal catalysis based on non-covalent catalyst-support interaction and an overview of the rapidly growing field of stereoselective dendrimer...