Heidi Klum rallied women at an event at The Grove in Los Angeles, promoting Clear Scalp & Hair Beauty Therapy's "Right End" campaign.
"One year ago, Clear Scalp & Hair Beauty Therapy turned haircare convention on its head by encouraging women to start working at the right end of hair, the scalp," said Klum.
Klum signed an oversized shampoo bottle, and invited attendees to follow suit.
"When we launched in the U.S. one year ago, it ushered in a completely new message and new way of thinking about haircare," said David Rubin, U.S. vice president, Haircare, Unilever.
Rubin continued "We kicked off in Los Angeles, but this is a nationwide movement that all women can take part in thanks to the connective power of social media."
The brand is inviting consumers to visit its Facebook page for a free product sample and chance to win a custom tote bag. Follow the brand on Twitter with the hashtag #RightEnd.