|Founded||April 18, 1984|
|Country|| United States |
|Number of teams||15|
Milwaukee Wave |
The National Professional Soccer League was a professional indoor soccer league in the USA and Canada. It was originally called the American Indoor Soccer Association.
After five years of study, a group called Soccer Leagues Unlimited, based in Kalamazoo, Michigan, first unveiled its plans for an indoor league, composed exclusively of American players, in November 1983. The group's president, Bob Lemieux (later AISA commissioner), announced that Kalamazoo, Fort Wayne and Springfield, IL were already on board in what was he said was intended to be a sort of farm system, or developmental league, for the well established Major Indoor Soccer League. He added that groups in Indianapolis, Peoria, and Michigan cities, Saginaw and Flint; Kentucky cities, Lexington and Louisville; Ohio cities, Columbus Toledo and Dayton; Erie, PA; and Green Bay, WI were all interested in the prospect of being a part such a league. 
Officially starting on April 18, 1984, the American Indoor Soccer Association's charter franchises were Chicago, Milwaukee, Kalamazoo and Fort Wayne,  however a Fort Wayne team did not actually materialize until the league's third season. Three other teams, Louisville, Canton and Columbus, all joined the league prior to the start of the first season in November 1984. The league changed its name to the National Professional Soccer League in 1990.  Over the course of 17 seasons, a total of 30 unique franchises in 32 different cities were part of the league at one time or another. During the summer of 2001, the league disbanded and the six surviving teams formed the second incarnation of the Major Indoor Soccer League. 
When the league began in 1984, game rules were almost identical compared to the larger and more popular MISL. Beginning with the 1988β89 season,  however, the AISA changed their scoring system. Goals were now worth 1, 2, or 3 points depending upon distance or game situation. Basically, all non-power play goals scored from inside the yellow line were worth 2 points while non-powerplay goals from outside the yellow line (50 feet from the goal line) were worth 3 points. Any power play goal was worth 1 point, as was any goal scored during a penalty shootout. Before the 1994β1995 season, the three-point line was changed to a 45-foot arc. Eventually, power play goals were worth either two or three points, but penalty shootouts were still kept at one point.
|1984β85||Canton Invaders||Louisville Thunder||3β1|
|1985β86||Canton Invaders||Louisville Thunder||3β0|
|1986β87||Louisville Thunder||Canton Invaders||3β2|
|1987β88||Canton Invaders||Ft. Wayne Flames||(Challenge Cup)|
|1988β89||Canton Invaders||Chicago Power||3β2|
|1989β90||Canton Invaders||Dayton Dynamo||3β1|
|1990β91||Chicago Power||Dayton Dynamo||3β0|
|1991β92||Detroit Rockers||Canton Invaders||3β2|
|1992β93||Kansas City Attack||Cleveland Crunch||3β2|
|1993β94||Cleveland Crunch||St. Louis Ambush||3β1|
|1994β95||St. Louis Ambush||Harrisburg Heat||4β0|
|1995β96||Cleveland Crunch||Kansas City Attack||4β2|
|1996β97||Kansas City Attack||Cleveland Crunch||4β0|
|1997β98||Milwaukee Wave||St. Louis Ambush||4β1|
|1998β99||Cleveland Crunch||St. Louis Ambush||3β2|
|1999β2000||Milwaukee Wave||Cleveland Crunch||3β2|
|2000β01||Milwaukee Wave||Philadelphia KiXX||3β0|
|Canton Invaders β Columbus Invaders β Montreal Impact||5||84β85, 85β86, 87β88, 88β89, 89β90||86β87, 91β92|
|Cleveland Crunch||3||93β94, 95β96, 98β99||92β93, 96β97, 99β00|
|Milwaukee Wave||3||97β98, 99β00, 00β01||β|
|Atlanta Attack β Kansas City Attack||2||92β93, 96β97||95β96|
|Louisville Thunder||1||86β87||84β85, 85β86|
|Tulsa Ambush β St. Louis Ambush||1||94β95||93β94, 97β98, 98β99|
|Dayton Dynamo β Cincinnati Silverbacks||0||β||89β90, 90β91|
|Fort Wayne Flames||0||β||87β88|
- Bob Lemieux 1984β1985
- Joe Machnik 1985β1988 
- Steve M. Paxos 1988β2000
- Steve Ryan 2000β2001
- Slater, Jim (November 4, 1983). "Ft. Wayne Will Be Charter Member in New Professional Soccer League". The Star Press. p. 21. Retrieved 20 June 2017 – via newspapers.com.
- "Soccer league planned". Southern Illinoisan. April 19, 1984. p. 15. Retrieved 20 June 2017 – via newspapers.com.
- "Canton wins final AISA crown". Milwaukee Sentinel. April 27, 1990. p. 5B. Retrieved 2012-05-04.
- "SOCCER: ROUNDUP; Rivaldo Gets Hat Trick; Barcelona Earns Victory". New York Times. August 9, 2001. Retrieved 2012-04-29.
- Bunch, Ken (July 11, 1988). "AISA adds franchises, MISL groups may apply". Milwaukee Sentinel. p. B1. Retrieved 2012-05-04.
- Lewis, Michael (2017-04-11). "Dr Joe Machnik: American soccer's renaissance man". The Guardian. ISSN 0261-3077. Retrieved 2017-08-05.