The anniversary? “I was thinking about it a little,” says composer Marti Epstein, whose new string quartet will be performed in Ozawa Hall on
Aug. 12, one of nine world premieres scheduled for Tanglewood’s 75th anniversary season. It’s an appropriate answer, since that’s how new music has seemed at Tanglewood: always there, but always somewhat in the back of its mind.

For many of the 75 years that the Boston Symphony Orchestra has summered at Tanglewood, new music was left primarily to the students, the fellows of the Tanglewood Music Center — and to the now-annual Festival of Contemporary Music, concentrating the newfangled into a convenient (and, for the hidebound, conveniently avoidable) week of concerts. The BSO would add a piece of token modernism to its program that week, but with the air of a nonplussed parent dutifully encouraging a child who insists on doing homework over summer vacation.

But birthdays bring out the BSO’s lingering taste for novelty. Anniversary commissions are a BSO custom, ever since Serge Koussevitzky ordered a birthday haul of estimable quality for the orchestra’s 50th anniversary, including one bona fide slice of immortality (Stravinsky’s “Symphony of Psalms,” which the BSO will perform under conductor Andris Nelsons July 13-15, the same weekend as Tanglewood’s 75th anniversary gala). Tanglewood’s 50th brought five new overtures from TMC alumni.

So the 75th, too, has produced a slate of commissions. The orchestral commemorations come, for the most part, courtesy of TMC faculty. The BSO has commissioned works from the current coordinator of the TMC composition program, Michael Gandolfi (“Night Train to Perugia,” Aug. 5), and its chairman, John Harbison (the intriguingly titled “Koussevitzky said:,” a chorus-and-orchestra curtain-raiser for the season-ending Aug. 26 performance of Beethoven’s Ninth). Frequent guest Andre Previn contributes “Music for Boston” (Aug. 10-11), and the TMC Orchestra will give two performances, July 8 and Aug. 13, of “Dreamscape,” by longtime TMC faculty head Gunther Schuller. (The BSO will also premiere Edgar Meyer’s Double Concerto, with violinist Joshua Bell and Meyer on double bass, on July 7.)

Recipients of TMC teaching will be represented by more compact fare. The Tanglewood Music Center has commissioned recent graduates to salt its Sunday morning chamber concerts: Ju Ri Seo’s “Concerto” for brass and percussion will be heard on July 1, while July 8 will bring both Matti Kovler’s “The Unbearable Lightness,” for seven double basses (Koussevitzky’s instrument) and Adam Roberts’s “Pasiphae Verses,” for 10 winds.

Epstein’s quartet, “Hidden Flowers,” will be the only premiere at this year’s Festival of Contemporary Music. Festival director Oliver Knussen is a Tanglewood stalwart, a former student who has returned again and again in both faculty and administrative guises. (Knussen was the composer in residence when Epstein was a TMC fellow: “I still think about the things he taught me,” she says.)

There are Tanglewood connections threaded throughout this year’s festival; it would be hard to avoid them. But the actual anniversary is more incidental to the programming, which instead is content to hew to a now-customary pattern: a younger contingent (both Epstein and Sean Shepherd, representing the United States, along with British composers Helen Grime and Luke Bedford), an older contingent (Harrison Birtwistle and George Benjamin are both represented by multiple works, along with performances of recent scores by Harbison, Elliott Carter, and Knussen’s own opera “Higglety Pigglety Pop!”), and a modernist-archeological contingent (there’s a special spotlight on the Italian composer Niccolò Castiglioni, who died in 1996, and Schuller will curate a concert of works by the ancient but ever-experimental Charles Ives).

The organizing principles — young and old, US and UK (like a musical Special Relationship) — seem more casual than the sort of stylistic line-in-the-sand that used to exercise compositional partisans back in the day, when Schuller and benefactor Paul Fromm clashed over the scope and breadth of festival programming. Now the week tries to make room for everything from Birtwistle’s dense, dissonant tapestries to Epstein’s still, contemplative processes — “a slower-moving sound world than usually programmed,” she proudly notes.

In its comparative normality, the 2012 festival might also be a bit of a breather: After the “Generation of ’38” retrospective in 2007, the celebration of Carter’s 100th birthday in 2008, and the marking of TMC’s 70th in 2010, the Festival of Contemporary Music has, perhaps, succumbed to a little anniversary fatigue — or is saving some strength for a TMC 75th in 2015.

Then again, maybe a non-commemorative festival is as good an anniversary present as any, a tribute to the under-the-radar but deep-rooted status of new music at Tanglewood, an embodiment of Koussevitzky’s vision of a place where music is continually renewed, summer after summer. As Epstein notes, new music at Tanglewood remains a celebration even without the amplified gaiety of a party hat: “That it happens is what’s so exciting.”