The We're the Millers actress, 22, hit the party with boyfriend, American Horror Story star Evan Peters, and channeled one of the most iconic movie characters of all time: Vivian Ward, the good-hearted prostituted immortalized by her aunt Julia Roberts in Pretty Woman, the smash 1990 film that made the actress, 45, a superstar. (Roberts was just 24 when was nominated for an Oscar for the role opposite Richard Gere.)
Specifically, Emma wore a blonde bob wig, knee-high leather boots, skimpy miniskirt and a white, midriff-baring tank top (featuring a gold ring that cinched the shirt to her skirt) as she held hands with Peters, who went to the bash as a cowboy.
Emma (whose actor dad Eric Roberts is Julia's older brother) has taken her very famous lineage in stride.
"I'm just doing my own thing," the Scream 4 actress told Us Weekly in 2011. "I don't really compare it to what my aunt does, but I do admire her and love all her movies."