Zac Efron & Lily Collins: Are They Dating?
02/07/2012 AT 07:45 PM EST
The actor and Lily Collins, 22, star of the upcoming film Mirror Mirror, were spotted enjoying dinner in Los Angeles at STK on Saturday, and they arrived together, according to a source.
"They even walked in holding hands," a source tells PEOPLE of the two, who were at the restaurant for a birthday party for one of Efron's friends.
"They had a drink at the bar together and then joined the birthday crew on the patio," the source adds.
Also hanging out with the birthday party posse: 90210's Ryan Rottman.
The same night, Efron, 24, was spotted partying at Hollywood hotspot Lexington Social House, where he greeted Miley Cyrus.
Two people he definitely isn't dating? Demi Moore and daughter Rumer.
"Me and Rumer have been friends for a long time. I know Demi is going through some personal stuff right now," the actor tells Extra. "I just wish her well. I hope she's doing okay."
Reporting by JENNIFER GARCIA