Although the character of the “lady detective”is a staple of the cozy mystery genre, we contend that there are no great lady detectives to rival Holmes or Poirot. This is not because there are no clever or interesting lady detective characters, but ratherbecause the concept of greatness is sociallyconstructed and, like coolness, depends on public acclaim and perception. We explore the mechanics of genre formation, arguing that the very structure of cozy mysteries precludes female greatness. To create a “great”character,theauthor cannot just endowher with certain attributes; she must actively work to overcome her audience’s tendency to import structures of oppression into the story, and she must wrestle against the conventions of the genre. In doing so, however, authors risk setting their stories in a wholly different genre.