In 2000, she starred in Guest's third mock documentary "Best in Show", and in the big budget horror film "Scream 3". Critical reaction to Posey's performance in the latter film was highly positive, and earned her an MTV Movie Award nomination. However, she lost to Adam Sandler, who won it for his performance in "Big Daddy". The next year she played the antagonist in "Josie and the Pussycats". From 2001-2002, she appeared in a supporting role in the popular NBC sitcom "Will & Grace".