After the passing of Jean Yawkey in February 1992, the Yawkey Trust continued to hold two of the team's three general partnership stakes, which it had done since buying out Buddy LeRoux's stake in 1987. In the wake of Mrs. Yawkey's passing, John Harrington served as trustee of the Yawkey Trust with sole authority over Red Sox matters. In 1993, the Yawkey Trust bought out Haywood Sullivan's stake in the club, giving John Harrington and the Yawkey Trust all three general partnership units and a 53.49% ownership in the team.
Before entering baseball, Harrington was an assistant professor at Boston College's Graduate School of Management. In 1970, Joe Cronin, the former player, manager and GM of the Red Sox, hired Harrington to be the controller for the American League, where Cronin was president. Tom Yawkey hired Harrington as the treasurer of the Red Sox in 1973 after the retirement of long-time Red Sox Treasurer Joe Cummiskey and Cronin's decision to move the AL offices to New York City. After Tom passed away, Harrington served as a trusted confidante to Mrs. Yawkey, particularly during the tumult of the 1980s, and became the club's CEO after her death.
Under Harrington's leadership, the Red Sox made the postseason in 1995, 1998 and 1999 and Fenway Park hosted the 1999 All-Star Game, one of the most memorable Midsummer Classics in history. Harrington also served as a negotiator for Major League owners during the Major League Baseball work stoppage of 1994-1995. In 2001, the Yawkey Trust sold the Red Sox to a group led by John Henry, Tom Werner and Larry Lucchino. After the sale, Harrington has continued to preside over the Yawkey Foundations, which under his supervision have contributed millions of dollars to Boston-area charitable causes and institutions.