A phylogeny including 26 families of Odonata is presented based on data from large and small subunit nuclear and mitochondrial ribosomal RNAs and part of the nuclear EF-1α. Data were analyzed using Bayesian methods. Extant Zygoptera and Anisoptera are monophyletic. The topology of Anisoptera is ((Austropetaliidae, Aeshnidae) (Gomphidae (Petaluridae ((Cordulegastridae (Neopetaliidae, Chlorogomphidae)) ((Synthemistidae, Gomphomacromiidae) (Macromiidae (Corduliidae s.s., Libellulidae))))))). Each of the major groups among anisopterans is well supported except the grouping of Neopeta lia with Chloropetalia. Lestidae and Synlestidae form a group sister to other Zygoptera, and Coenagrionoidea are also monophyletic, with the caveat that Isostictidae, although well supported as a family, was unstable but not placed among other coenagrionoids. Calopterygoidea are paraphyletic and partly polytomous, except for the recovery of (Calopterygidae, Hetaerinidae) and also (Chlorocyphidae (Epallagidae (Diphlebiinae, Lestoidinae))). Support for Epallagidae as the sister group of a clade (Diphlebiinae, Lestoideinae) is strong. Within Coenagrionoidea, several novel relationships appear to be well supported. First, the Old World disparoneurine protoneurids are nested within Platycnemididae and well separated from the protoneurine, Neoneura. The remaining coenagrionids are divided into two well-supported subdivisions. The first includes Pseudostigmatinae, stat. nov., Protoneurinae, a group of coenagrionids mostly characterized by having an angulate frons, and Argiinae (Argia). The second division includes typical Coenagrionidae.