In 2005, the NCAA ended its official association with summer collegiate baseball; however, the CICL continued to preserve the amateur status of its member athletes by abiding by the rules and regulations of the National Alliance of College Summer Baseball (NACSB).

[1] In 2009, the CICL planned to expand to six teams by adding the Hannibal Cavemen, but in winter 2008, the league ownership voted against further expansion.

The Prospect League began its inaugural season in summer 2009 with the original CICL teams forming the Western Division.

[4] In 2010, the Prospect League expanded adding four new franchises: the Terre Haute Rex (Terre Haute, Indiana), the West Virginia Miners (Beckley, West Virginia), the DeKalb County Liners (Sycamore, Illinois), and the Nashville Outlaws (Nashville, Tennessee).

[5] Due to a change in team ownership in 2010, the North Coast Knights became the Lorain County Ironmen.

[11][12][13] For the 2017 season, the league contracted to 10 teams, as the Hannibal Cavemen and DuPage Drones both ceased operation.

The West Division consisted of the Cape Catfish, DuPage Pistol Shrimp, Hannibal Hoots, Normal CornBelters, Quincy Gems and the Springfield Sliders.

The East Division consisted of the Champion City Kings, Chillicothe Paints, Danville Dans, Lafayette Aviators, Terre Haute REX and the West Virginia Miners.

[20] In January 2020, the league announced adding a new team in Alton, Illinois for the 2021 season.

[22] In February 2021, the league announced the addition of two new teams in Iowa, the Clinton LumberKings and Burlington Bees.

[28] Charter members: Butler BlueSox, Champion City Kings (as the Slippery Rock Sliders), Chillicothe Paints, Danville Dans, DuPage Dragons, Hannibal Cavemen, Richmond RiverRats, Springfield Sliders, Quincy Gems The Cape Catfish, DuPage Pistol Shrimp and Normal CornBelters joined the league in the 2019, replacing the Kokomo Jackrabbits, who left for the Northwoods League,[29] and the Butler BlueSox, who suspended operations.

Winners from each half in each division faced each other in a one-game playoff (home field to team with best overall record).

The remaining two divisional playoff winners met in a one-game play-in for the right to go to the Championship Game.