Vagaceratops was named by Scott D. Sampson, Mark A. Loewen, Andrew A. Farke, Eric M. Roberts, Catherine A. Forster, Joshua A. Smith, and Alan L. Titus in 2010, and the type species is Vagaceratops irvinensis.
 This species was originally described as a species of Chasmosaurus (C. irvinensis) in 2001.
Its relationships remain debated.
Vagaceratops has variously been allied with Kosmoceratops or with Chasmosaurus.

The cladogram below is the phylogeny of the Chasmosaurinae by Brown et al (2015):
Vagaceratops was named by Scott D. Sampson, Mark A. Loewen, Andrew A. Farke, Eric M. Roberts, Catherine A. Forster, Joshua A. Smith, and Alan L. Titus in 2010, and the type species is Vagaceratops irvinensis.  This species was originally described as a species of Chasmosaurus (C. irvinensis) in 2001. Its relationships remain debated. Vagaceratops has variously been allied with Kosmoceratops or with Chasmosaurus.
The cladogram below is the phylogeny of the Chasmosaurinae by Brown et al (2015):
Vagaceratops