My major research interests are the phylogenetic relationships, classification and evolution of Hymenoptera, and the methodology of phylogenetic inference itself. The primary focus of this work is the wasp family Vespidae, where I am pursuing a worldwide revision based on cladistic analysis of the entire group. The Vespidae are a large and important group, of considerable general interest because it contains one of the major radiations of eusocial insects. My papers are the first rigorous studies of the phylogeny of social wasps, and so are of particular interest to behaviorists and evolutionary biologists working with social insects. Beyond this, my published studies on Vespoidea and Chrysidoidea are among the early explicitly cladistic investigations of the higher level phylogeny of Hymenoptera, while work both published and in progress on vespid genera will be one of the first comprehensive such treatments of any family in the order. This latter work includes some of the first empirical applications of quantitative cladistic techniques such as successive weighting or incongruence length difference testing. In addition, I have used published results to produce a critical test of models for the evolution of social behavior in wasps, among of the first applications of cladistics to testing complex evolutionary scenarios.