Billboard Hot 100 Fest

POTW: Rihanna, Justin Bieber, Katy Perry, Lady Gaga, No Doubt

July 20: Rihanna poses with her momma and grand-momma backstage during the LOUD 2011 Summer Tour.

Rihanna gets frisky with her mother, Katy Perry goes cowgirl, Lady Gaga takes on Howard Stern and No Doubt and Major Lazer hit the studio. It all happened this week, and we've got the pics to prove it.

SEE THE PHOTOS OF THE WEEK | LAST WEEK'S PHOTOS

News of the Week: Billboard's 5 Most Popular Stories

1. Poll: Best '90s Video?


2. Tastemakers: Bruno Mars


3. Bruno Mars: The Billboard Cover Story

4. LMFAO Still Atop Hot 100, Demi Lovato Debuts In Top 10

5. 10 Awesome Auto-Tuned Tracks