Using data from more than 10,000 games from 1985 through 2009, the authors estimate the effect various factors have on attendance at Major League Baseball (MLB) games. As previously found in the literature, interleague and interleague rivalry contests are associated with higher attendances, but this relationship has been weakening over time. Contrary to some of the literature, the authors find that the likelihood the home team will win the contest is inconsistently estimated over time, lending little support for the uncertainty of outcome hypothesis. Generally the effect on ticket sales from many potential factors has generally been weakening over time.