Last night, a slew of Hollywood's best dressed ladies stepped out in exceptional style to support a very worthy cause at the Hollywood Stands Up To Cancer Benefit. With event chairs Reese Witherspoon and Jim Toth, it's no surprise they were able to wrangle an A-list group of guests to help raise funds for Stand Up To Cancer's research programs. From floral jumpsuits to leather dresses, click through to see who rocked our top seven looks of the night (plus where to score the styles!) in today's Best Dressed Guests.