To Dye Or Not to Dye?

Either everyone in Hollywood has forgotten to touch up their roots or we have a new trend on our hands...Two-tone hair, or dip-dye hair, is quickly becoming a favorite trend. These 7 celebs show how its done:Rachel Bilson:

Drew Barrymore:

Olivia Palermo:

Lauren Conrad:

Isabel Lucas

Scarlett Johanssen shows how you can subtly follow the trend with a less drastic change in colour:

Whitney Port and Lo Bosworth rock the dip-dye pony tail:

And Nicki Minaj takes dip-dye to a whole new level: