(Photo: Gallery Books)

Sheryl Lee Ralph is one of those rare actresses in Tinsletown that bridges the gap between old Black Hollywood and current day. At age 19 she made her film debut opposite Sidney Poitier and Bill Cosby in 1977's A Piece of the Action. Ralph was later nominated for originating the role of Deena Jones in the Broadway production of Dreamgirls in 1982. And by 1996 she was America’s favorite stepmom on the Brandy vehicle Moesha. Today the 55-year-old Ralph chronicles her career and the lessons learned from it in her candid new memoir, Redefining Diva: Life Lessons From the Original Dreamgirl.

The mother of two spoke to BET.com about her new book, working with the legendary Poitier, the best career advice she got from Robert DeNiro and why she can't wait to work with ABC show creator Shonda Rhimes.

In Redefining Diva you were very candid about your beef with Diana Ross, who didn’t like that your Dreamgirls character was loosely based on her. And you also had issues with Brandy, which ultimately led to you exiting Moesha. Were you ever concerned about including those items in the book?

I hope that folks understand that no matter what, I have great admiration for Diana Ross and Brandy. But you know how you have a family of people and sometimes you get on each other’s nerves? That does not mean I love you any less. It’s just that we had a run-in right there and it was very real. It will either bring us closer together or it will move us further apart.

Ultimately those moments allowed you to become closer to both women. But is it really true that you left Moesha because Brandy didn’t like the fact that you wore braids one season?

It started with a lot of things I didn’t agree with. But I’ve had to deal with a different phenomenon my whole life and that’s been people saying to me, ‘Just shut up.’ Stars don’t have a point a view. Shut up, you’re beautiful, can’t you just be satisfied with that? Shut up, why do you always have to have an opinion about things? It’s a constant I've learned the hard way. Sometimes doing the right thing or standing up for yourself doesn’t really matter.

Tell me what it was like to work with the legendary Sidney Poitier in your first feature film.

Mr. Poitier is just amazing for me. When I auditioned for him it was like, 'Wow, my mother’s dream, my father’s dream come true and my community’s dream just came true, because I was in a room with Sidney Poitier!' I’ve also had the wonderful experience of working with Mr. Bill Cosby, who’s always been supportive of me and has continued to say over the years, 'I know it’s hard but keep on.' And I’ve worked with Whoopi [Goldberg] over and over again. Whoopi and I seemed to be like two estranged sisters. We’re the same people on the flipside of the coin.

Another screen legend you collaborated with, Robert DeNiro, had some tough career advice when you two worked together in 1992's Mistress, right?

Yes. We were together in-between scenes and we were just sitting there, waiting for them to set up the next shot. He wasn’t looking at me, he was looking out of the window and he said, ‘You really deserve some kind of an award for this performance. You’re really good. You better wave that red flag because they’re not looking for you [the Black girl.]' So that was hard. I got it, I understood it but I was kind of shocked. I was like, ‘Wow, OK.' That was 19 or 20 years ago.

You’ve been honored repeatedly for the past three decades you’ve spent as an AIDS activist. What’s the most unusual thing people ask you about this work?

People still ask me why do you do this? What’s wrong with you? I do it because I saw people suffer and die, get sick and drop dead. And I saw what it was like when there was no help to come.

After 30 years they’re still waiting to hear something like I’m positive or something. I’m not HIV positive but I’m a very positive person. I care because I’m a human being.

Your 33 years on TV has included your work on such classic hit shows like The Jeffersons, It’s a Living and Designing Women. What would you like to do next on the small screen?

I can’t wait until the Black queen of TV  Shonda Rhimes hires me. I cannot wait until she reads my book. [Our show could be about] a strong Black woman who was able to play the game and tell the truth.

Redefining Diva: Life Lessons From the Original Dreamgirl arrives in bookstores and can be downloaded on March 13.

For more information, visit:

http://www.sherylleeralph.com/

Or Follow Sheryl on Twitter at:

@TheSherylRalph

@ARedifiningDiva

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(Photo: Frederick M. Brown/Getty Images)