Recently the singer-songwriter Rufus Wainwright's first opera, Prima Donna, premiered at England's Manchester International Festival.

The reviews have been respectful of Mr. Wainwright, but mixed regarding the opera itself. Some critics have found fault with Mr. Wainwright's orchestrations or his contrapuntal passages, while praising his melodic gifts.

But times have changed, as Wainwright is at least being given credit for attempting a grander form than the artful pop songs that have been his métier. 

In the 20th century, composers such as George Gershwin and Leonard Bernstein incorporated popular music into their classical works. This wasn't a new thing. Mozart and others used popular music, but the modern era in music had turned into something much more conservative about certain forms of borrowing. We're past the time when elitists sniff at Gershwin (for the most part), but the classical world remains reluctant to embrace serious efforts by pop composers.

Pop music has been much more inclusive of other styles than contemporary classical music generally has, maybe because it's easier for a pop musician to quote or nod to other genres of music since pop is so much looser than classical music. The Beatles were fans of Stockhausen, and also helped introduce Indian music to a global audience. Yet when Paul McCartney's Liverpool Oratorio premiered back in 1991, some questioned whether a mere pop composer should try to horn in on the territory of composers better trained for this sort of music.

Yet that didn't stop the album from becoming a big seller on the classical charts. And since then, Sir Paul has written and released four other popular classical-oriented works, Paul McCartney's Standing Stone, Paul McCartney's Working Classical and Ecce cor Meum.

Someone of Paul McCartney's accomplishments doesn't need to write classical music, nor does he necessarily need the acknowledgement of classical critics. Something else is at work here. Like a host of musicians with long careers, he is driven to create in a variety of forms, outside his comfort zone, to stay fresh.

Or perhaps he just likes this kind of music. Joni Mitchell said in an interview regarding The Fiddle and the Drum, which she wrote for Alberta Ballet and Canadian choreographer Jean Grand-Maître, "Classical music, with its complexity, becomes more satisfying as you get older."

Some pop composers, like Billy Joel, listened to classics when they were younger, in his case 19th-century and early 20th-century piano music. That influenced his songwriting, with its strong melodic sense, but once he felt that he had said what he had to as a songwriter, Joel turned to instrumental forms. In 2001, Joel released Fantasies & Delusions, a well-received CD of his classical-style piano pieces, performed by Richard Joo, that showed the influence of Chopin, among others. Later, pianist Jeffrey Biegel created a piano concerto using selections from Fantasies & Delusions.

The singer-songwriter Elvis Costello, like Rufus Wainwright, has had classical leanings. In the early 1990s, his collaboration with the Brodsky Quartet resulted in an interesting album, The Juliet Letters, which sounded more lieder-like than rock. (He also coaxed the opera singer Anne Sofie von Otter into crossover territory, writing an album of music for her, For the Stars, which was released on Deutsche Grammophon.) He has written ballet music, too, including Il Sogno, after Shakespeare's A Midsummer Night's Dream, commissioned by the Italian dance troupe Aterballeto. And Danish Royal Opera commissioned him to write an opera about Hans  Christian Andersen's fascination with the Swedish songbird Jenny Lind.

This is all to the good, since whatever the ultimate success of these various projects from pop composers, they undoubtedly bring attention to the forms (ballet, oratorio, opera) that can use publicity to attract audiences; they help excellent songwriters remain passionate about writing, and they can actually produce some worthwhile work.