Studies reveal consistent relationships between personality and preferred musical genre. This article explores these relationships using a novel methodology: genre dispersion among people’s mobile-phone music collections. By analyzing the download behavior of genre-based user subgroups, we investigated the following questions: (1) do genre-based subgroups exhibit different levels of genre exclusivity; and (2) does genre exclusivity relate to Big Five personality factors? We hypothesized that genre-based subgroups would vary in genre exclusivity, and that their degree of exclusivity would be associated with the personality factor of openness (if people have open personalities, they should be open to different musical styles). Consistent with our hypothesis, results showed that greater genre inclusivity, that is, many genres in people’s music collections, positively correlated with openness and (unexpectedly) agreeableness, suggesting that individuals with high openness and agreeableness have wider musical tastes than those with low openness and agreeableness. By demonstrating an association between personality and patterns of music consumption, this research serves to corroborate previous work linking genre preference and personality. The practical implications of this research may be useful in the implementation of music-recommendation systems.