Genre discourse is widespread in appreciative practice. It should be no surprise then, that philosophers of art have also been interested in genre and in genres. However, in their accounts, philosophers have so far focused on capturing all of the categories of art that we think of as genres and have focused less on ensuring that only the categories we think are genres are captured by those theories. Each of these theories populates the world with far too many genres because they call a wide class of mere categories of art genres. I call this the problem of genre explosion. In this paper, I survey the existing accounts of genre and describe the kinds of considerations they employ in determining whether a work is a work of a given genre. After this, I demonstrate the ways in which the problem of genre explosion arises for all of these theories and discuss some solutions those theories could adopt that will ultimately not work. Finally, I argue that the problem of genre explosion is best solved by adopting a social view of genres, which can capture the difference between genres and mere categories of art.