Highlights of the company's early history include: the first-ever joint BBC/WNET telecast of Albert Herring; the first appearance by any U.S. opera company at the 1983 Edinburgh International Festival; and the Japanese premiere of Joruri in Tokyo, the first production of a Japanese opera in Japan by any American company. The company returned to Tokyo in September 2001 to present the Japanese premiere of Minoru Miki's The Tale of Genji.

Well-known directors Graham Vick, Jonathan Miller, and Mark Lamos made U.S. operatic debuts with Opera Theatre, as did conductor Leonard Slatkin. OTSL productions have been career milestones for outstanding U.S. singers including Christine Brewer, Susan Graham, Dwayne Croft, Patricia Racette, Kallen Esperian, Nathan Gunn, Mary Dunleavy, and many others.

Opera Theatre has always been known for adventurous productions, and for its commitment to bringing new works into the opera repertory. By the 2009 season the company will have presented 21 world premiere operas (all but two of them  commissioned by OTSL) and 22 American premiere productions - which is perhaps the highest percentage of new work in the repertory of any U.S. company. OTSL has presented important revivals of American landmarks including Vanessa, Transformations, Treemonisha, and Miss Havisham's Fire; the new 2004 production of John Adams's Nixon in China was seen again at seven other companies. Critics hailed OTSL's US premiere production of Walton's Troilus and Cressida in 2008; the new version of John Corigliano's The Ghosts of Versailles, one of the Metropolitan Opera's greatest hits at its premiere in 1991, will be a highlight of the upcoming 2009 OTSL season and will be seen again at Vancouver Opera and Ireland's Wexford Festival Opera.