In 2004, the league relaunched with six teams in six markets: California Sunbirds in Stockton, California; Arizona Heat in Tucson, Arizona; Texas Thunder in Houston, Texas; Akron Racers in Akron, Ohio ; New England Riptide in Lowell, Massachusetts; and NY/NJ Juggernaut in Montclair, New Jersey.

Today, there are 5 National Pro Fastpitch teams: the Aussie Peppers, the California Commotion, the Chicago Bandits, the Cleveland Comets, and the Canadian Wild.

The season concluded the last weekend in August when the Akron Racers beat the Chicago Bandits 5–4 in extra innings to claim the NPF Championship Title.

The Brakettes, the Akron Racers, the 2005 Regular Season Champions, the Chicago Bandits, the New England Riptide, the Arizona Heat, the Texas Thunder competed in league play during 2006.

The league announced that the Pennsylvania Rebellion would be added as an expansion team for the 2014 season, receiving the roster of the recently defunct NY/NJ Comets.

The Dallas–Fort Worth metroplex-based team will split their home games between the Ballfields at Craig Ranch in McKinney and a ballpark in Arlington.

[6] On October 23, 2015, the NPF announced that the Scrap Yard Dawgs would join the league as an expansion team based in The Woodlands, Texas.

Its roster is to be populated with members of China women's national softball team and selected American players.

[11] In an arrangement similar to the Beijing Eagles', NPF announced in December 2017 that Softball Australia would be operating a 2018 expansion team, the Aussie Spirit.

[18] On November 14, 2019, the California Commotion was announced to be an expansion team, representing the league's first presence on the west coast since the 2005 season.

[20][21] On August 1, 2021, the league announced that, due to a lack of revenue after cancelling the previous two seasons, it would be suspending operations.

Former LPGA Tour member Janie Blaylock, softball legend Joan Joyce, tennis icon Billie Jean King, sports entrepreneur Jim Jorgensen and Dennis Murphy co-founder of the WHA and WTT leagues, founded the International Women's Professional Softball Association (IWPSA) in 1976.

The league featured 10 teams in cities across the nation, including Meriden, Connecticut, Chicago, Illinois, Prescott, Arizona, and San Jose, California.

The fledgling association survived four seasons before lack of funds, high travel costs, and inadequate facilities ultimately led to its demise.

In 1982, the National Collegiate Athletic Association began to sanction the Women's College World Series, a move that led to increased participation and exposure for the sport.

In January 1994, plans for a barnstorming tour were announced, and 18 months later two teams, the Blaze and the Storm, composed of former collegiate all-stars played exhibition games in cities throughout the Midwest.

Eight years of research and planning finally culminated in May 1997, with the Cowles family and title sponsor AT&T Wireless Services launching Women's Pro Fastpitch (WPF).

The world's most talented fastpitch softball players, including former Olympians, collegiate All-Americans, and all-conference selections highlighted the 15-player rosters of the league's four squads.

The Akron Racers, Florida Wahoos,[n 1] Ohio Pride, and the Tampa Bay FireStix each participated in the WPSL regular season.

Play was suspended during the 2002 season to restructure the organization and allow the league additional time to develop and explore new expansion markets.