The National Professional Soccer League was a professional indoor soccer league in the USA. It started out as the American Indoor Soccer Association in 1984 but changed its name to the National Professional Soccer League in 1990. During the summer of 2001, the league disbanded and the six surviving teams formed the second version 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 1988-89 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 1994–1995 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.