The family Caenagnathidae, together with its sister group the Oviraptoridae, comprises the superfamily Caenagnathoidea.
In phylogenetic taxonomy, the clade Caenagnathidae is defined as the most inclusive group containing Chirostenotes pergracilis but not Oviraptor philoceratops.
While before 2010s only about two to six species were commonly recognized as belonging to the Caenagnathidae, currently that number may be much greater, with new discoveries and theories about older species that may inflate this number to up to ten.
Much of this historical difference centers on the first caenagnathid to be described, Chirostenotes pergracilis.
Due to the poor preservation of most caenagnathid remains and resulting misidentifications, different bones and different specimens of Chirostenotes have historically been assigned to a number of different species.
For example, the feet of one species, named Macrophalangia canadensis, were known from the same region from which Chirostenotes pergracilis was recovered, but the discovery of a new specimen with both hands and feet preserved provided the support to combine them, while the later discovery of a partial skull with hands and feet  suggested that Chirostenotes and Caenagnathus were the same animal, and current studies of caenagnathid relationships continue to find them as closely related genera.

 
Longrich and colleagues (2013) defined a subgroup of Caenagnathidae, the Caenagnathinae, as all caenagnathids more closely related to Caenagnathus collinsi than to Caenagnathasia martinsoni or Elmisaurus rarus.
In 2015, the group Elmisaurinae was defined, including all species more closely related to Elmisaurus rarus than to Caenagnathus collinsi.

The cladogram below follows an analysis by Funston & Currie in 2016.
The family Caenagnathidae, together with its sister group the Oviraptoridae, comprises the superfamily Caenagnathoidea. In phylogenetic taxonomy, the clade Caenagnathidae is defined as the most inclusive group containing Chirostenotes pergracilis but not Oviraptor philoceratops. While before 2010s only about two to six species were commonly recognized as belonging to the Caenagnathidae, currently that number may be much greater, with new discoveries and theories about older species that may inflate this number to up to ten. Much of this historical difference centers on the first caenagnathid to be described, Chirostenotes pergracilis. Due to the poor preservation of most caenagnathid remains and resulting misidentifications, different bones and different specimens of Chirostenotes have historically been assigned to a number of different species. For example, the feet of one species, named Macrophalangia canadensis, were known from the same region from which Chirostenotes pergracilis was recovered, but the discovery of a new specimen with both hands and feet preserved provided the support to combine them, while the later discovery of a partial skull with hands and feet  suggested that Chirostenotes and Caenagnathus were the same animal, and current studies of caenagnathid relationships continue to find them as closely related genera.
 
Longrich and colleagues (2013) defined a subgroup of Caenagnathidae, the Caenagnathinae, as all caenagnathids more closely related to Caenagnathus collinsi than to Caenagnathasia martinsoni or Elmisaurus rarus. In 2015, the group Elmisaurinae was defined, including all species more closely related to Elmisaurus rarus than to Caenagnathus collinsi.
The cladogram below follows an analysis by Funston & Currie in 2016.
Caenagnathidae