I think I got all of them down, but even after searching I haven’t been able to find a complete list in the order they appear. I even tried watching a YouTube video (with a slow dial-up connection) that claimed to label each singer but it didn’t show the later singers. I’m trying to positively identify the 2nd to last singer, right after Bruce Springsteen’s 2nd solo part and before Ray Charles’ 2nd solo part (and the last solo part of the song). Is that Jeffrey Osborne? Someone else? Did I flub any of the other identifications?
Lionel Richie
Stevie Wonder
Paul Simon
Kenny Rogers
James Ingram
Tina Turner
Billy Joel
Michael Jackson
Diana Ross
Dionne Warwick
Willie Nelson
Al Jarreau
Bruce Springsteen
Kenny Loggins
Steve Perry
Daryl Hall
Michael Jackson (again)
Huey Lewis
Cyndi Lauper
Kim Carnes
Bob Dylan
Ray Charles
Stevie Wonder (again)
Bruce Springsteen (again)
???
Ray Charles (again)
http://youtube.com/watch?v=clZE4Wrrw_w
Lionel Richie
Lionel Richie/Stevie Wonder
Stevie Wonder
Paul Simon
Paul Simon/Kenny Rogers
Kenny Rogers
James Ingram
Tina Turner
Billy Joel
Billy Joel/Tina Turner
Michael Jackson
Diana Ross
Diana Ross/Michael Jackson
Dionne Warwick
Dionne Warwick/Willie Nelson
Willie Nelson
Al Jareau
Bruce Sprinsteen
Kenny Loggins
Steve Perry
Daryl Hall
Michael Jackson (again)
Huey Lewis
Cindy Lauper
Kim Carnes
Kim Carnes/Huey Lewis/Cindy Lauper
ALL
Bob Dylan
ALL
Bob Dylan (again) sings w/ALL
Ray Charles sings w/ALL
Ray Charles
Stevie Wonder sings w/Bruce Springsteen
Stevie Wonder (again)
Stevie Wonder sings w/Bruce Springsteen
Bruce Springsteen (again)
ALL
James Ingram sings w/Ray Charles
James Ingram (again)
Ray Charles (again)
ALL
ALL sings w/Ray Charles (again)
I loved singing this song, but could not do in my own voice. I would mimic the voices of the singers. I still remember all the words, order of singers & how they sang their part. Thanks for the smile. 
My drama class performed this in high school. I was absent the day everyone got their parts, and returned the next day to find that the only role left was Lionel Richie. No one else wanted him because he sings first. And that is how a scrawny little white girl in a sweater vest came to represent Lionel… :o
A bit of trivia…this song is still pretty popular here in Cameroon. Always feels a bit absurd when they play it.
Wow, so that was James Ingram again. It looks like he changed his shirt / windbreaker. The first appearance looks more metallic and the second looks like bright white.
Thanks!
Heh. About two years ago a buddy of mine and I would listen to this song frequently on our drives to/from work. Between the two of us, we had pretty solid imitations of every singer.
As a slight aside, if one is abreast of the Jimmy Kimmel/Matt Damon “feud,” and saw Sarah Silverman’s I’m Fucking Matt Damon video, one might have missed the follow up by Jimmy Kimmel, which in the final minutes parodies this song. They even have Huey Lewis reprise his role in the original. It’s pretty sweet!
In fact, it’s just one guy. His name is André-Philippe Gagnon.