| Period | Members | Releases |
| February – December 1967(as The Big Thing) | Robert Lamm – keyboards, vocals Terry Kath – guitar, vocals Danny Seraphine – drums, percussion Walter Parazaider – woodwind, backing vocals Lee Loughnane – trumpet, backing vocals James Pankow – trombone, backing vocals | none |
| December 1967 – June 1968(as The Big Thing) | Robert Lamm – keyboards, vocals Terry Kath – guitar, vocals Peter Cetera – bass, vocals Danny Seraphine – drums, percussion Walter Parazaider – woodwind, backing vocals Lee Loughnane – trumpet, backing vocals James Pankow – trombone, backing vocals |
| June 1968 – mid-1969(as Chicago Transit Authority) | Robert Lamm – keyboards, vocals Terry Kath – guitar, vocals Peter Cetera – bass, vocals Danny Seraphine – drums, percussion Walter Parazaider – woodwind, backing vocals Lee Loughnane – trumpet, backing vocals James Pankow – trombone, backing vocals | Chicago Transit Authority (1969) |
| Mid-1969 – early-1974 | Robert Lamm – keyboards, vocals Terry Kath – guitar, vocals Peter Cetera – bass, vocals Danny Seraphine – drums, percussion Walter Parazaider – woodwind, backing vocals Lee Loughnane – trumpet, backing vocals James Pankow – trombone, backing vocals Touring musicians Laudir de Oliveira – percussion (1973–1974) | Chicago (1970) Chicago III (1971) Chicago at Carnegie Hall (1971) Chicago V (1972) Chicago VI (1973) Chicago VII (1974) |
| Mid-1974 – January 1978 | Robert Lamm – keyboards, vocals Terry Kath – guitar, vocals Peter Cetera – bass, vocals Danny Seraphine – drums Walter Parazaider – woodwind, backing vocals Lee Loughnane – trumpet, backing vocals James Pankow – trombone, backing vocals Laudir de Oliveira – percussion, congas | Chicago VIII (1975) Chicago X (1976) Chicago XI (1977) Chicago XXXIV: Live in '75 (2011) |
| April 1978 – February 1980 | Robert Lamm – keyboards, vocals Peter Cetera – bass, vocals Donnie Dacus – guitar, vocals Danny Seraphine – drums Walter Parazaider – woodwind, backing vocals Lee Loughnane – trumpet, backing vocals James Pankow – trombone, backing vocals Laudir de Oliveira – percussion | Hot Streets (1978) Chicago 13 (1979) |
| February 1980 – late 1981 | Robert Lamm – keyboards, vocals Peter Cetera – bass, vocals Danny Seraphine – drums Walter Parazaider – woodwind, backing vocals Lee Loughnane – trumpet, backing vocals James Pankow – trombone, backing vocals Laudir de Oliveira – percussion Chris Pinnick – lead guitar Touring musicians Marty Grebb – saxophone, guitar, keyboards, backing vocals (1980–1981) | Chicago XIV (1980) |
| Late 1981 – July 1985 | Robert Lamm – keyboards, vocals Peter Cetera – bass, vocals Bill Champlin – keyboards, guitar, vocals Danny Seraphine – drums Walter Parazaider – woodwind, backing vocals Lee Loughnane – trumpet, backing vocals James Pankow – trombone, backing vocals Chris Pinnick – lead guitar Touring musicians Kenny Cetera – percussion, keyboards, backing vocals (1984–1985) | Chicago 16 (1982) Chicago 17 (1984) |
| September 1985 – July 1986 | Robert Lamm – keyboards, vocals Bill Champlin – keyboards, guitar, vocals Jason Scheff – bass, vocals Danny Seraphine – drums Walter Parazaider – woodwind, backing vocals Lee Loughnane – trumpet, backing vocals James Pankow – trombone, backing vocals | Chicago 18 (1986) |
| July 1986 – May 1990 | Robert Lamm – keyboards, vocals Bill Champlin – keyboards, guitar, vocals Jason Scheff – bass, vocals Dawayne Bailey – lead guitar, backing vocals Danny Seraphine – drums Walter Parazaider – woodwind, backing vocals Lee Loughnane – trumpet, backing vocals James Pankow – trombone, backing vocals | Chicago 19 (1988) |
| May 1990 – late 1994 | Robert Lamm – keyboards, vocals Bill Champlin – keyboards, guitar, vocals Jason Scheff – bass, vocals Dawayne Bailey – lead guitar, backing vocals Tris Imboden – drums, percussion, harmonica Walter Parazaider – woodwind, backing vocals Lee Loughnane – trumpet, backing vocals James Pankow – trombone, backing vocals | Twenty 1 (1991) Chicago XXXII: Stone of Sisyphus (2008) |
| December 1994 – January 1995 | Robert Lamm – keyboards, vocals Bill Champlin – keyboards, guitar, vocals Jason Scheff – bass, vocals Bruce Gaitsch – lead guitar Tris Imboden – drums, percussion, harmonica Walter Parazaider – woodwind, backing vocals Lee Loughnane – trumpet, backing vocals James Pankow – trombone, backing vocals | Night & Day: Big Band (1995) |
| January 1995 – mid-2009 | Robert Lamm – keyboards, vocals Bill Champlin – keyboards, guitar, vocals Jason Scheff – bass, vocals Keith Howland – lead guitar, backing vocals Tris Imboden – drums, percussion, harmonica Walter Parazaider – woodwind, backing vocals Lee Loughnane – trumpet, backing vocals James Pankow – trombone, backing vocals | Chicago XXV: The Christmas Album (1998) Chicago XXVI: Live in Concert (1999) A&E Network: Live by Request (2003) Live in Concert... (2003) Live at the Greek Theatre (2004) Chicago XXX (2006) Chicago XXXV: The Nashville Sessions (2013) |
| Mid-2009 | Robert Lamm – keyboards, vocals Bill Champlin – keyboards, guitar, vocals Jason Scheff – bass, vocals Keith Howland – lead guitar, backing vocals Tris Imboden – drums, harmonica Drew Hester – percussion Walter Parazaider – woodwind, backing vocals Lee Loughnane – trumpet, backing vocals James Pankow – trombone, backing vocals | none |
| August 2009 – May 2012 | Robert Lamm – keyboards, vocals Jason Scheff – bass, vocals Lou Pardini – keyboards, vocals Keith Howland – guitar, backing vocals Tris Imboden – drums, harmonica Drew Hester – percussion Walter Parazaider – woodwind, backing vocals Lee Loughnane – trumpet, backing vocals James Pankow – trombone, backing vocals | Chicago XXXIII: O Christmas Three (2011) |
| May 2012 | Robert Lamm – keyboards, vocals Jason Scheff – bass, vocals Lou Pardini – keyboards, vocals Keith Howland – guitar, backing vocals Tris Imboden – drums, harmonica Daniel de los Reyes – percussion Walter Parazaider – woodwind, backing vocals Lee Loughnane – trumpet, backing vocals James Pankow – trombone, backing vocals | none |
| May 2012 – October 2016 | Robert Lamm – keyboards, vocals Jason Scheff – bass, vocals Lou Pardini – keyboards, vocals Keith Howland – guitar, backing vocals Tris Imboden – drums, harmonica Walfredo Reyes Jr. – percussion Walter Parazaider – woodwind, backing vocals Lee Loughnane – trumpet, backing vocals James Pankow – trombone, backing vocals | Chicago XXXVI: Now (2014) Chicago at Symphony Hall (2015) |
| October 2016 – June 2017 | Robert Lamm – keyboards, vocals Lou Pardini – keyboards, vocals Jeff Coffey – bass, vocals Keith Howland – guitar, backing vocals Tris Imboden – drums, harmonica Walfredo Reyes Jr. – percussion Walter Parazaider – woodwind, backing vocals Lee Loughnane – trumpet, backing vocals James Pankow – trombone, backing vocals | none |
| June 2017 – January 2018 | Robert Lamm – keyboards, vocals Lou Pardini – keyboards, vocals Jeff Coffey – bass, vocals Keith Howland – guitar, backing vocals Tris Imboden – drums, harmonica Walfredo Reyes Jr. – percussion Ray Herrmann – woodwind, backing vocals Lee Loughnane – trumpet, backing vocals James Pankow – trombone, backing vocals | Chicago II Live on Soundstage (2018) Greatest Hits Live (2018) |
| January – May 2018 | Robert Lamm – keyboards, vocals Lou Pardini – keyboards, vocals Neil Donell – vocals, acoustic guitar Keith Howland – lead guitar, backing vocals Brett Simons – bass, backing vocals Walfredo Reyes Jr. – drums Daniel de los Reyes – percussion Ray Herrmann – woodwind, backing vocals Lee Loughnane – trumpet, backing vocals James Pankow – trombone, backing vocals | none |
| May 2018 – December 2021 | Robert Lamm – keyboards, vocals Lou Pardini – keyboards, vocals Neil Donell – vocals, acoustic guitar Keith Howland – lead guitar, backing vocals Brett Simons – bass, backing vocals Walfredo Reyes Jr. – drums Ramon "Ray" Yslas – percussion Ray Herrmann – woodwind, backing vocals Lee Loughnane – trumpet, backing vocals James Pankow – trombone, backing vocals | Chicago XXXVII: Chicago Christmas (2019) Chicago XXXVIII: Born For This Moment (2022) |
| December 2021 - January 2022 | Robert Lamm – keyboards, vocals Lou Pardini – keyboards, vocals Neil Donell – vocals, acoustic guitar Brett Simons – bass, backing vocals Walfredo Reyes Jr. – drums Ramon "Ray" Yslas – percussion Ray Herrmann – woodwind, backing vocals Lee Loughnane – trumpet, backing vocals James Pankow – trombone, backing vocals Tony Obrohta - lead guitar, backing vocals | none |
| January – March 2022 | Robert Lamm – keyboards, vocals Neil Donell – vocals, acoustic guitar Brett Simons – bass, backing vocals Walfredo Reyes Jr. – drums Ramon "Ray" Yslas – percussion Ray Herrmann – woodwind, backing vocals Lee Loughnane – trumpet, backing vocals James Pankow – trombone, backing vocals Tony Obrohta - lead guitar, backing vocals Touring musicians Loren Gold – keyboards, backing vocals (2022) |
| March – April 2022 | Robert Lamm – keyboards, vocals Neil Donell – vocals, acoustic guitar Brett Simons – bass, backing vocals Walfredo Reyes Jr. – drums Ramon "Ray" Yslas – percussion Ray Herrmann – woodwind, backing vocals Lee Loughnane – trumpet, backing vocals James Pankow – trombone, backing vocals Tony Obrohta - lead guitar, backing vocals Loren Gold – keyboards, vocals |
| May 2022 – March 2025 | Robert Lamm – keyboards, vocals Neil Donell – vocals, acoustic guitar Walfredo Reyes Jr. – drums Ramon "Ray" Yslas – percussion Ray Herrmann – woodwind, backing vocals Lee Loughnane – trumpet, backing vocals James Pankow – trombone, backing vocals Tony Obrohta – lead guitar, backing vocals Loren Gold – keyboards, vocals Eric Baines – bass, vocals |
| March 2025 – present | Robert Lamm – keyboards, vocals Neil Donell – vocals, acoustic guitar Walfredo Reyes Jr. – drums Ramon "Ray" Yslas – percussion Ray Herrmann – woodwind, backing vocals Lee Loughnane – trumpet, backing vocals James Pankow – trombone, backing vocals Tony Obrohta – lead guitar, backing vocals Loren Gold – keyboards, vocals Eric Baines – bass, vocals Carlos Murguia - keyboards, vocals |