By Leah Ornstein – Radar Style & Beauty Editor

From the Los Angeles premiere of one of this summer’s hottest comedies to the streets of NYC, stars were dressed to rock and shock this Monday – and RadarOnline.com has all the photos.

PHOTOS: The Best & Worst Fashions Of The Day

At The Change-Up premiere, Leslie Mann looked white hot in a Marchesa cocktail dress, while Olivia Wilde opted for a red hot Antonio Berardi number.  Ryan Reynolds’ pal Sandra Bullock made an understated appearance on the carpet, rocking a snazzy Lanvin jumpsuit with oodles of cool jewels.

PHOTOS: The Best, Worst & Wackiest Fashions Of The Weekend

Mischa Barton landed herself the worst look of the day, looking like she had a bad encounter with a paper shredder in Los Angeles in her crazily cut up jean shorts.

PHOTOS: Mischa Barton Hits The Carrera Sunglasses Escape Event

A la mode misses included Lady Gaga, who went overboard in Salvatore Ferragamo houndstooth print, and Dianna Agron, who committed a style sin by wearing velvet in the summer.

For all the rest of the best and worst looks of the day, click here.