With the advent of user-generated content and the capabilities of current information and communication technologies, indexing and retrieval tools for music should facilitate discovery that transcends genre boundaries. Nonetheless, they still privilege genre as the primary mode of categorization. Even recommender systems, which utilize other measures to determine similarity, give the appearance of drawing upon genre. By examining the ambiguous boundaries and definitions of genres, the contexts in which indexing and retrieval tools for music have developed, and the roles played by music at individual and societal levels, this paper considers alternative traits that could act as indicators of “similarity.”