The Peoria Chiefs are a Minor League Baseball team of the Midwest League and the High-A affiliate of the St. Louis Cardinals. The team was established in 1983 as the Peoria Suns. They are located in Peoria, Illinois, and are named for the Peoria Indian tribe for which the city was named. In 2005, the team replaced the indigenous imagery associated with the Chiefs name and moved to a logo of a dalmatian depicted as a fire chief. The Chiefs play their home games at Dozer Park, which opened in 2002. They previously played at Vonachen Stadium near Bradley University from 1983 through 2001. The Chiefs have made the playoffs a total of 13 times, through eight wild-card berths, three first-half titles, and two second-half titles.

High-A, officially Class High-A, formerly known as Class A-Advanced, and sometimes abbreviated "A+" in writing, is the third-highest level of play in Minor League Baseball in the United States and Canada, below Triple-A and Double-A, and above Single-A. There are 30 teams classified at the High-A level, one for each team in Major League Baseball (MLB), organized into three leagues: the Midwest League, Northwest League, and South Atlantic League.