Jennifer Simpson (née Barringer; born August 23, 1986) is a retired American middle- and long-distance runner.

Barringer finished 3rd in San Diego's Foot Locker Cross Country Championships in 2003 behind winner Katelyn Kaltenbach of Colorado and Marie Lawrence of Nevada.

At the time of the event, this performance made her the third-fastest female 1500 m runner in U.S. track and field history.

[12] Barringer came fifth at the 2009 World Championships in Athletics, running a North American record time of 9:12.50 minutes for the event.

While at Colorado, she won the Honda Sports Award as the nation's best collegiate female track and field athlete in 2009.

[13][14] Despite the fact that she could have signed a professional contract, Barringer returned to school in the fall of 2009 to compete in cross country.

[30] Simpson claimed the USATF Outdoor 5000 meter title in 15:33.77 in the 95+ degree heat of Des Moines, Iowa on June 23.

[33] Simpson was runner-up at the Boston New Balance Indoor Grand Prix 2 mile after miscounting her laps to finish in 9:26.19 on February 8.

[36] On July 4, Simpson became the 2nd fastest American 1500 meter runner by running 3:57.22 at a Diamond League race in Paris.

[37] With two wins late in the season, including a dramatic diving finish at the Weltklasse Zürich, she won the 2014 IAAF Diamond League.

At the Herculis Diamond League meet at Stade Louis II in Monaco Simpson ran 3:57.30, just .18 off Mary Slaney's nearly 32-year-old American record before the race.

On September 11, at the Diamond League finale in Brussels, Simpson placed 4th in the mile in 4:22.18, just behind Shannon Rowbury who finished in 4:22.10.

[45] By the end of the year, she ran the 3000 meters standard[46] for the 2016 IAAF World Indoor Championships in the 3000 metres[47] at the Zürich Diamond League.

[49] Simpson ran a 4:19.98 mile, finishing 5th at the London Anniversary Games on July 9, 2017, behind Hellen Obiri and Laura Muir, Winny Chebet and Angelika Cichocka, setting a personal record, and second fastest time ever for an American woman.

Simpson capped her 2017 campaign with a record-setting win at the New York Road Runners Fifth Avenue Mile.

[52] On September 8, 2019, Simpson bettered her best time in the Fifth Avenue Mile, running 4:16.1 to give her sole possession of the event record.