The River City Rascals began play in the 1993 season as the Zanesville Greys in Zanesville, Ohio, as part of the Independent Frontier League. The Greys won the Frontier League title in 1993 and became the Frontier League’s first champions. The Greys moved to the newly built T.R Hughes Ballpark in O’Fallon, Missouri, in 1999 where they were given the new name of the River City Rascals. The Rascals began play in the Frontier League under the leadership of three former major leaguers: manager Jack Clark, pitching Coach Greg Mathews, and first-base coach Dick Schofield Jr. The Rascals made their O'Fallon debut on Tuesday, June 8, 1999, at T.R. Hughes Ballpark in front of a crowd of 4,173. The team led the Frontier League in home runs in 1999 and averaged more than 150,000 fans in 1999, and set new franchise records for attendance in 2000 and 2002. The Rascals were named Frontier League Organization of the Year in 1999 and 2000.
The Rascals were purchased in 2007 by a group led by long-time minor league baseball executive Steve Malliet. Malliet served as President and General Manager of the team until 2009 before transitioning to the position of President of the Normal Cornbelters (also of the Frontier League). Toby Rumfield, who previously worked with the Cincinnati Reds, was hired to be the manager of the Rascals in 2007 and was replaced a year later by Chad Parker, the former manager of the Macon Music. Under Parker, the 2009 Rascals went on to win 56 games and clinch the division title. Parker was named the Frontier League Coach of the Year in 2009 as well.
In the 2010 season, Steve Brook, a former decorated Rascals pitcher, replaced Parker as manager. That year, the Rascals finished second in the Western Division and won the Frontier League Championship Series for the first time in franchise history. The Rascals have had casinon continued success under Brook clinching Western Division titles in 2011 and 2014, as well as making appearances in the Frontier League Championship in 2011, 2014, 2015, and 2016. The Rascals have seen the transition to CarShield Field as naming rights sponsor of the stadium and the addition of a synthetic turf playing surface. They are under the direction of General Manager, Lisa Ferreira.
Major League Rascals
- Terry Pearson (1995-96): Detroit Tigers
- Jack Clark (Rascals Manager, 1999-2000): Hitting Coach of the Los Angeles Dodgers
- Josh Kinney (2001): St. Louis Cardinals, Chicago White Sox, Seattle Mariners
- Justin Christian (2003-04): New York Yankees, San Francisco Giants
- Joe Thatcher (2004-05): San Diego Padres, Arizona Diamondbacks, Los Angeles Angels, Houston Astros
- Brandon Cunniff (2011-13): Atlanta Braves, Miami Marlins
(2009) 56-38 West Division Champions/ Frontier League Championship Appearance
(2010) 57-38 Frontier League Champions
(2011) 68-27 West Division Champions/Frontier League Championship Appearance
(2014) 61-36 West Division Champions/Frontier League Championship Appearance
(2015) 56-40 Frontier League Championship Appearance
(2016) 54-51 Frontier League Championship Appearance