James Conlon, music director of the Ravinia Festival since 2005,will leave his post after the 2015 season.

Ravinia is the summer home of the Chicago Symphony Orchestra, which concluded its 2014 season there on Aug. 17. Conlon, 64, also is the music director of the Los Angeles Opera and the Cincinnati May Festival.

Conlon’s contract was to expire after this summer but he agreed to a one-year extension. “Everything has its time, and after 11 years, I feel it is the moment to pass on this responsibility,” Conlon said in a statement released Aug. 26. “This has been a difficult decision. The work at Ravinia is very meaningful to me, and the CSO is a supreme orchestra. I have worked year-round, including every summer, since 1974. There are things I wish to accomplish, both musical and personal, and I need dedicated time to realize these projects.”

He thanked Ravinia president and CEO Welz Kauffman, “who graciously understood and accepted my decision, and will arrange for a smooth transition.”

To honor Conlon’s long association with Ravinia, where he first appeared as a guest conductor in 1977, the 2015 season will celebrate major themes of his tenure, including works by Mahler, Mozart, Wagner and composers represented in Conlon’s Breaking the Silence series, an offshoot of his Recovered Voices Project. Both champion works suppressed by the Nazi regime.

Conlon will launch his 2015 Ravinia season on July 22, with a program replicating his 1977 debut there: Mozart’s Piano Concerto No. 23, K. 488, and Mahler’s Symphony No. 1. Garrick Ohlsson will be the soloist in the Mozart. On July 29, Conlon will reprise Zemlinsky’s The Mermaid, which he conducted at Ravinia in 2007. He will close out his Ravinia tenure with a concert performance Aug. 15 of Wagner’s The Flying Dutchman, which has never been performed in its entirety at the festival.

Though a search will get under way soon for Conlon’s successor, Kauffman said there is no timetable. “The only decision we’ve made at this point is to not rush into a decision,” he said. “Such transitions present a rare opportunity to take a fresh look at who we are and what we do in these challenging times for classical music. We know from our audiences that they enjoy seeing a variety of guest conductors leading the CSO, so we will take our time.”