The purpose of our study is to compare how fans react to rivalry across different professional sports leagues. We surveyed a total of 4,247 fans of teams in Major League Baseball (MLB), Major League Soccer (MLS), the NFL, and the National Hockey League (NHL) to measure dis-identification toward the top rival of respondent's favorite team, as well as prejudice, relationship discrimination, and schadenfreude toward that rival team's fans. We also measured the level of fan identification with each respondent's favorite team. The results reveal a strong pattern of greater animosity toward rivals among NFL fans compared with fans of other leagues.