The Harlequins formed in 1971. The team name is a tribute to Harlequin F.C., an English club that competes in the Aviva Premiership. In 1972, the Harlequins became the first Texas RFU club to win a match against a club from outside the United States when they defeated the Baillou Club of Nassau, Bahamas. Though the Dallas Harlequins had begun using the Harlequin name upon formation, they did not become formally affiliated with Harlequins FC until 1983, marking the first time that a club from the western hemisphere had formed an official relationship with the team for whom they were named. Dallas Hosted the Mexican National 7's Side in the summer of 2008. Harlequins Dylan Carrion and Mike Ashmead both scored in this contest.
Harlequins who have played for the USA national team include Brett 'Rangi' Pedersen, David 'Motor' Care, Brett 'Rosey' Taylor, Bruce 'Monkey' Monroe, Jason Engelbrecht, Taylor Mokate, Justin Boyd, Blake Rodgers, and Bob Olsonoski.
Harleqiuns who have represented The Western United States Rugby Territory select side include Brett Taylor, Bruce 'Monkey' Monroe, Ed 'Spyk' Gheur, Bob 'Ludo' Lutterbach, Norbert Mueller, Steve Ryan, Duane "Tiny" Watts, Bob Saunders, Phil Waterman, Bob Waterman, Mark Carrion, Johan Van Rensburg, Brian Driscoll, Jess Marshall, Jason Engelbrecht, Taylor Mokate, Justin Boyd, and Blake Rodgers.
In addition, long standing Dallas Harlequin Bob Latham has held numerous positions in sports, including Vice Chairman and former Chairman of USA Rugby, former member of Board of Directors of US Olympic Committee, President of North America Caribbean Rugby Association, Director and former President of Dallas All Sports Association, and Vice President of Pan American Rugby Association.
One of the Harlequin's main sponsors is Crispin Cider. In addition to Crispin, Dallas Harlequins RFC has individual sponsorships. Notable primary sponsors include Plains Capital Bank. The club also has several secondary sponsorships from local and regional businesses such as Texas State Movers, which is owned by former U19 Harlequin Colts coach George Munstedt and Accede Construction, owned and operated by loyal Quins Jess and Andrew Marshall.