Don Henley in session

“I’m still foolish enough to think that my best work is ahead of me,” Eagles co-founder Don Henley said during a private playback session for his forthcoming solo album “Cass County.” An audience of a few dozen listeners filled rows of chairs set up in Capitol Records’ historic Studio A in Hollywood Thursday night for the session, during which eight songs — half the 16 tracks on the deluxe edition of the album to be released this fall — were played.

What they heard was a strongly country-leaning set in which Henley is joined by mainstream country and Americana musicians including Miranda Lambert, Martina McBride, Trisha Yearwood, Merle Haggard, Lucinda Williams, Vince Gill and yes, even Mick Jagger. Jagger and Lambert team up with Henley on Tift Merritt’s “Bramble Rose,” which Henley pointed out reflected Jagger’s longtime passion for American country music, stretching back to when he and Keith Richards struck up a friendship with country-rock pioneer Gram Parsons.

The album, Henley’s first solo record in 15 years, was finished a year ago but had to wait to be released until Henley completed obligations with “that other band I play in.” He said he doesn’t know how to categorize it, but “I tried to make the kind of album I’d like to hear on country radio.”