Ice Bucket Challenge: Gwen Stefani, Jessica Alba, Nicole Richie

Jessica Alba, Gavin Rossdale and Nicole Richie get drenched as they take the ALS Ice Bucket Challenge. Pic: Instagram

Gwen Stefani prepared to dump a bucket of ice cold water over her husband and friends. Pic: Instagram

Jessica Alba Pic: Instagram

Jessica, Gavin and Nicole get prepared for the soaking. Pic: Instagram

Taylor and Jaime poured their buckets of water over each other. Pic: Instagram

Justin Bieber Pic: Instagram

Selena Gomez Pic: Instagram