The Ides of March actress, who came out as bisexual earlier this year, said that she felt it was only right to reveal her sexuality in order to help other girls who might be in her position.
"That's for real. I've been that way since I can remember," Wood explained to GQ.
"I remember growing up and loving when I knew there was a girl like me who I looked up to. I figured I should return the favour. You don't have to be ashamed."
Wood previously revealed that she was initially "terrified" of dating women as she felt "intimidated" by them.
The 24-year-old, who was once engaged to rocker Marilyn Manson, is recently said to have reunited with ex-boyfriend Jamie Bell.
Watch a trailer for The Ides of March below: