"Since joining Glimmerglass Opera as music director in 1988, I have had the good fortune of working with many of the most talented people in this industry," Robertson said in a statement. "I have spent a significant portion of my life at Glimmerglass Opera, and the company will always hold an incredibly special place in my heart. There are still, however, many things I would like to explore in my career, and this seems like the ideal time to pursue such endeavors."

During his tenure at Glimmerglass, the highly regarded summer festival in Cooperstown, New York, Robertson has focused on the operas of Benjamin Britten and on new American works: he conducted the world premieres of William Schumann's A Question of Taste; David Carlson's Midnight Angel; Robert Beaser, Deborah Drattell, and Michael Torke's three-part Central Park; and Stephen Hartke and Philip Littell's The Greater Good.

Robertson founded and directed Glimmerglass's Young American Artists Program, which trained such singers as Christine Goerke, Michelle deYoung, and Isabel Bayrakdarian.

Trained at the Royal Scottish Academy of Music, Robertson previously served as music director of the Santa Fe Symphony, San Bernardino Symphony, Zurich Ballet, and Scottish Opera Touring Company. He frequently appears as a guest conductor and has led world premieres at the Lyric Opera of Chicago, Opera Theatre of St. Louis, Utah Opera, and Scottish Opera.

"Stewart's departure after the 2006 festival season is certain to be bittersweet for all of us," said Peter Duchin, Glimmerglass's board chair. "While we wish him all the best as he moves on to pursue other endeavors, his musical excellence and commitment to the discovery and development of young American singers have played an integral part in the company's ascent to international stature. "