On Tuesday night, the pair were seen dancing, eyes locked, before kissing and making out as bodyguards shooed the crowd away, PEOPLE reports in its upcoming issue.
Earlier in the evening Aniston, 36, showed up at the Vic Theatre, where Vaughn, 35, brought his Wild West Comedy Show tour. During the performance, Aniston watched from the balcony. (She also caught his show Sept. 16 in Oxnard, Calif., after they filmed the comedy The Break Up this summer.) Her favorite part: when Vaughn showed an old clip of himself performing in an ABC After School Special about sex.
At the party after the show, Vaughn grabbed Aniston around the waist, pulled her to his side and told a few friends, "She's the best!" while rubbing her back. He later gave her a kiss on the temple, and the two proceeded to make out.
At the time, Aniston's rep denied a romance between the two, telling PEOPLE, "Do not read into this. At the wrap party . . . everyone was enjoying themselves, cast and crew included, and they were all being very affectionate to each other."
Aniston, meanwhile, has declared herself ready to date again, telling Oprah Winfrey that she is open to whatever comes her way. "I love the unknown. I love the discovery of what will be happening and just kind of sitting back and not knowing," she said last month.
Aniston's divorce from Brad Pitt was finalized on Oct. 2.