Chase Field, formerly Bank One Ballpark, is a retractable roof stadium in downtown Phoenix, Arizona, United States. It is the ballpark of Major League Baseball's Arizona Diamondbacks. It opened in 1998, the year the Diamondbacks debuted as an expansion team. Chase Field was the first stadium built in the United States with a retractable roof over a natural grass playing surface, although it has used artificial turf since 2019.

The park was built during a wave of new, baseball-only parks in the 1990s. Although nearly all of those parks were open-air, it was taken for granted that a domed stadium was a must for a major-league team to be viable in the Phoenix area. Phoenix is by far the hottest major city in North America; the average high temperature during baseball's regular season is 99.1 °F (37.3 °C), and game-time temperatures well above 100 °F (38 °C) are common during the summer.

In the spring of 1994, the Maricopa County Board of Supervisors approved a 0.25 percentage point increase in the county sales tax to pay for their portion of the stadium funding. That happened during a huge county budget deficit and lack of funding for other services. The sales tax was very unpopular with local citizens, who were not permitted to vote on funding a baseball stadium with general sales tax revenue (use of public subsidies for stadium projects was prohibited by a 1989 referendum). The issue was so controversial and divisive that, in August 1997, Maricopa County Supervisor Mary Rose Wilcox was shot and injured while leaving a county board meeting by Larry Naman, a homeless man, who attempted to argue in court that her support for the tax justified his attack. In May 1998, Naman was found guilty of attempted first-degree murder.

The cost of the stadium was estimated at $279 million in 1995, but cost overruns, in part because of rising prices for steel and other materials, pushed the cost to $364 million. As part of the stadium deal, the Diamondbacks were responsible for all construction costs over $253 million. The extra expenses, combined with the Diamondbacks and the other expansion franchise, the Tampa Bay Devil Rays, not being allowed to share in national MLB revenue for their first five years of operations, left the Diamondbacks in a less-than-desirable financial situation, which came back to haunt team founder and managing partner Jerry Colangelo and his group.

Construction on the park began in 1996, and was finished just before the Diamondbacks' first season, in 1998. It was the third MLB stadium to have a retractable roof and the first in the United States (at the time, only Toronto's SkyDome (Rogers Centre) and Montreal's Olympic Stadium had them; others since are Daikin Park in Houston, American Family Field in Milwaukee, Globe Life Field in Arlington, T-Mobile Park in Seattle, and LoanDepot Park in Miami). It was also the first ballpark to feature natural grass in a retractable roof stadium.

The stadium hosted Games 1, 2, 6, and 7 of the 2001 World Series between the Arizona Diamondbacks and the New York Yankees. The Diamondbacks won all four home games, winning the title in seven games, and thus denying the Yankees a fourth consecutive championship. It was only the third time that the home team won all games of a World Series, with the other two instances occurring in 1987 and 1991, both by the Minnesota Twins.

In March 2006, Chase Field played host to three first-round games of the World Baseball Classic.

Chase Field hosted the Major League Baseball All-Star Game in 2011.