Becoming a "member" of the 40-40 club is one of the most elusive achievements in modern American sports, as players that possess either the power to hit 40 home runs or the speed to steal 40 bases in a season are a rarity in and of themselves. This remains true even as statistical trends change in baseball; stolen base totals in the 1980s were unusually high, but very few players reached 40 home runs, and home run totals were extremely high in the late 1990s, but stolen bases became more and more rare as the steal became a much more sparingly used tactic.
As such, only three players in history can claim membership in the 40-40 club. They are:
Members of the 40-40 club are already members of the 30-30 club.