Triatominae, the kissing bugs, are one of the smaller subfamilies of the otherwise predatory hemipteran family Reduviidae, the assassin bugs. Substantial progress has been made during the past decades to resolve phylogenetic relationships between Triatominae and other reduviid subfamilies as well as relationships among the ~150 species currently classified as kissing bugs. Nevertheless, many open questions remain. While Triatominae are now shown to be part of an assassin bug clade that also comprises Stenopodainae and part of Reduviinae, it is still not conclusively established if Triatominae are monophyletic or paraphyletic, and there are uncertainties with regard to relationships between and within tribes of Triatominae. This chapter summarizes available information on the evolution of Triatominae, highlighting strengths and shortcomings of currently published phylogenetic hypotheses. It stresses the importance of densely sampled, data-rich, robust phylogenies to inform the classification of Triatominae and to severe as a framework for evolutionary investigations across the group.