A cladistic analysis based on mitochondrial DNA and morphology of 40 species of Polistes is presented. Thirty-six New World species are treated with attention to classical taxonomic views, including subgeneric, species-group, and species membership. No previously proposed species groups are supported. Variants that have been sometimes thought conspecifics, including P. erythrocepahlus and P. infuscatus, are found to be more distinct than earlier taxonomy would suggest. Combination of morphology and molecules often provides stronger support for certain groupings, including a North American clade of the former Fuscopolistes. These results indicate that some morphological signal emerges only when the DNA and morphological data are analyzed together. Our results support the dissolution of all New World subgenera into a single subgenus, Aphanilopterus.