“Welcome to the world-famous Apollo Theater,” the usher says as he takes your ticket for Jazz at Lincoln Center’s fourth annual Summer Gala – although I’m not sure when it stopped being just the Apollo and the words “world-famous” became officially part of the name. I was surprised that Jazz at Lincoln Center would continue to use the Apollo for such events, since their own Rose Hall has better sound and sight lines. Still, three previous years of hosting the gala obviously count for something, and I think it’s a tradition worth upholding.

As all-star events go, theJ@LCgala is a model of efficiency – the events are typically 70 minutes long and hosted by a famous actor who is also a jazz fan (in this case, Don Cheadle). They feature an array of mainstream music stars along with major personalities from the jazz world, all backed by Wynton Marsalis and his septet (Mr. Marsalis, trumpet; Wycliffe Gordon, trombone; Wess Anderson, alto sax; Victor Goines, tenor sax; Carlos Henriquez, bass; and a new pianist, 23-year-old Dan Nimmer.)

The spotlight inevitably shines on stars from country and pop, but celebrity guests generally work hard to make their music relevant. Highlights of previous galas included what was probably Ray Charles’s last appearance in New York (in 2003) and the only time I was ever able to actually understand Bob Dylan (in 2004). With nearly all of the guests, there is a welcome give and take – something essential to the spirit of jazz, and something that makes Jazz at Lincoln Center events more than just benefits where headliners parade their hits.

The two country stars who began and ended Monday night’s program were a good case in point. Lyle Lovett sang two of his signature pieces in new arrangements with the Marsalis Septet, “My Baby Don’t Tolerate” and “In My Own Mind.” Wynonna Judd closed with two jazz standards. The gala also included the Blind Boys of Alabama, a marvelous vocal quintet with harmonies that are authentic and mellow. Here they were enhanced by elaborate introductions (especially from Mr. Gordon on tuba). They were outstanding on “The Last Time,” but on “If I Had a Hammer,” they fell into the same routine they too often do in their own concerts, inciting the audience to stand up, sing along, and clap.

Robert Downey Jr. sang an original and a standard (“Smile,” co-composed by Charlie Chaplin, whom Mr. Downey once portrayed).The trouble with famous actors who want to impress you as singers is that we can’t help feeling like they’re still playing somebody. Sympathetic and charming as he was, Mr. Downey seemed to be playing Michael Bolton doing Ray Charles. Tenor giant James Moody provided a more genuine note, playing a swinging 12-bar blues and doing new shtick on his classic “Mood for Love” routine.

The great surprise was Tom Jones. I had always thought of the 1960s popster as the Welsh Elvis – he was glitzy long before Presley went that route. But Mr. Jones showed he certainly understands the blues. He began with his mega-hit, “It’s Not Unusual,” in which the musicians merely played the standard chart without any solos. But then he fully collaborated with the band on two blues specialties, the traditional “St. James Infirmary” and Big Joe Turner’s “Sally Zu-Zazz” (a variation on “Roll ‘Em”), a boogie-woogie specialty perfectly in sync with Mr. Jones’s customary shuffle beat.

Mr. Jones made us all feel that his hometown, Pontypridd, South Wales, must be somewhere near Kansas City. He whetted my appetite for a full-length performance in a jazzblues context. Nothing unusual about it.