From BR Bullpen
The term "club" is used rather loosely, as it is generally used by sports writers and fans to group players together under a common heading. The word "club" was likely coined based on the original exclusiveness and rarity of a 30-30 season. Statistically, the 30-30 club is of note due to the pairing of power and speed - two measurements usually isolated from one another. For example, a slugging first baseman would not usually accumulate high stolen base totals. Likewise, a speedy center fielder may be more adept at stealing bases, but may not supply much power. Thus, many players may be able to either steal 30 bases or hit 30 home runs, but only a rare handful may be able to do both.
 Trends and Breakdown
Recent trends show that club membership has steadily increased since the 1970s. Ken Williams was the first player to reach the mark in the major leagues in 1922 with 39 home runs and 37 stolen bases. He was the sole member of the club for 34 years until Willie Mays had back-to-back 30-30 seasons in 1956 and 1957. Occurrences then began to increase thereafter, as there were 2 in the 1960s, 5 (4 by Bobby Bonds) in the 1970s, 7 in the 1980s, 20 (5 by Barry Bonds) in the 1990s, and 17 (4 by Alfonso Soriano) in the 2000s.
Most 30-30 seasons come from players who play the outfield, particularly left and right field. However, several center fielders have enjoyed 30-30 seasons, including Willie Mays, Dale Murphy, Eric Davis, Preston Wilson, Carlos Beltran, Grady Sizemore, Jacoby Ellsbury, Matt Kemp and Mike Trout. The remaining breakdown is as follows: shortstop (4) (Barry Larkin, Alex Rodriguez, Jimmy Rollins, Hanley Ramirez); third base (3) (Tommy Harper, Howard Johnson, David Wright); second base (3) (Alfonso Soriano, Brandon Phillips, Ian Kinsler); first base (2) (Joe Carter, Jeff Bagwell). There has not been a 30-30 season recorded by a player who predominately plays catcher or pitcher.
 30-30 Seasons in the majors
40-40 club seasons in bold.
 Notes and Trivia
- A 20-20 season (20 home runs and 20 stolen bases) is also of note, however it is much more common. A 20-20 season is usually noticed on a local level by sports writers or team officials, especially if the player is a second baseman or catcher. The first and only 20-20 season by a catcher was attained by Ivan Rodriguez in 1999 with 35 home runs and 25 stolen bases.
- There have been four seasons in which four separate players recorded 30-30 seasons. The first was 1987 (Joe Carter, Eric Davis, Howard Johnson, and Darryl Strawberry). The second was 1996 (Dante Bichette, Barry Bonds, Ellis Burks, and Barry Larkin). The third was in 1997 (Jeff Bagwell, Bonds, Raul Mondesi, and Larry Walker). The last occurance was in 2011 (Ryan Braun, Jacoby Ellsbury, Matt Kemp, and Ian Kinsler). The most recent season without a 30-30 player was 2013. The closest 30-30 player in 2010 was Carlos Gonzalez with 34 home runs and 26 stolen bases. Other recent seasons where a player did not record a 30-30 season include 1994 - the season shortened by the player's strike. In 1994 Barry Bonds finished with 37 home runs and 29 stolen bases (112 games), while Sammy Sosa also had a shot with 25 home runs and 22 steals (105 games). During the shortened 1981 season, Andre Dawson finished with 24 home runs and 26 steals in 103 games.
- The players with the most 30-30 seasons are Bobby Bonds and his son Barry with 5 each. The only other players with more than 2 are Alfonso Soriano with 4, and Howard Johnson with 3. Players with two 30-30 seasons: Willie Mays, Ron Gant, Sammy Sosa, Jeff Bagwell, Raul Mondesi, Vladimir Guerrero, Bobby Abreu, Ian Kinsler and Ryan Braun.
- The rarer 30-40 season has been repeated only by Bobby Bonds (4), Barry Bonds (2), and Alfonso Soriano (2), the 40-30 season only by Barry Bonds (2) and Jeff Bagwell (2), and only Barry Bonds and Alfonso Soriano have had at least one 40-30 and one 30-40 season. There have been only two 30-50 seasons (Eric Davis and Barry Bonds), and no 50-30 seasons. For more elite seasons, see the 40-40 club.
- The 30-30 season has only been accomplished by two players on the same team during the same season twice: the New York Mets in 1987 and the Colorado Rockies in 1996.
- There is a nightclub in Manhattan, New York with the name "Club 30-30", however this name is presumed to be based on the address (which is 30-30), and not the grouping of baseball players. The rapper/CEO Jay-Z owns a nightclub named "The 40-40 Club", also located in Manhattan. The name is based on the 40-40 club, implying a sense of prestige and exclusiveness .
 First player to reach 30-30 in different minor leagues and international leagues
(far from complete)
- Jeromy Burnitz, Eastern League, 1991
- Jim Steels, Mexican League, 1991
- Jae-hong Park, Korea Baseball Organization, 1996
- Chih-Sheng Lin, Chinese Professional Baseball League, 2015