Heard, the "Pineapple Express," who will soon appear as Johnny Depp's love interest in "The Rum Diaries," came out Friday at GLAAD's 25 anniversary celebration, where she walked the red carpet with her girlfriend of two years, artist and photographer Tasya van Ree.
Afterward, speaking to the gay-centered entertainment site AfterEllen.com, Heard said she felt a responsibility to come out at 24.
""I think when I became aware of my role in the media, I had to ask myself an important question, 'Am I part of the problem?'" she told the the website.
"I think that the injustice of people staying in the closet is more than I can bear with a clear conscience," Heard said, "and I couldn't sleep at night if I was a part of that problem, if I was part of the lies."
Asked about van Ree, Heard said, "She's so beautiful. I mean, you'd have to be crazy not to want to go out with her!"
Heard was recently photographed at a rally against California's Proposition 8, which bans gay marriage. She called the fight for gay rights "our generation's civil rights movement," adding, "If we're too scared to come out and say who we are, we'll never get anywhere."
Apparently, other celebrities agree. There's been a recent flood of stars -- from Anna Paquin to Ricky Martin -- coming out of the closet and embracing their true sexuality. And Hollywood seems to be welcoming them.
Paquin, who's engaged to her "True Blood" co-star Stephen Moyer, revealed in April that she's bisexual in a PSA released Thursday for the the "Give a Damn" campaign, which features stars speaking out for equality.
"I'm Anna Paquin. I'm bisexual and I give a damn," Paquin says to the camera. Paquin's publicist declined to comment on the PSA or the actress' sexuality.