Stephen Colletti headed to Sin City for a birthday celebration with his girlfriend and co-star Chelsea Kane at 1 OAK at the Mirage.
Seated in the same VIP booth that Fergie partied at on New Year’s Eve, just behind the DJ booth, Colletti and Kane danced the night away with a group of their friends including “One Tree Hill” creator Mark Schwahn.
Toward the end of the evening, Colletti was surprised when 1 OAK presented him with an extravagant Jean Phillippe birthday cake. The crew hung at the club until just after 3 a.m. before retreating to their suites.

Stephen Colletti and girlfriend Chelsea Kane attend the 'One Tree Hill' Final Season cocktail reception during the CW portion of the 2012 Television Critics Association Press Tour at The Langham Huntington Hotel and Spa on January 12, 2012 in Pasadena, California.

Chelsea Kane and Stephen Colletti arrive at the 2011 MTV Movie Awards at Universal Studios' Gibson Amphitheatre on June 5, 2011 in Universal City, California.
Looks like things are really heating up with these two! They were spotted in Vegas over the Memorial Day weekend taking in a performance of Phantom: The Las Vegas Spectacular. After the performance, the duo met the stars of the production Anthony Crivello (The Phantom) and Kristen Hertzenberg (Christine).

Spotted: Stephen Colletti and girlfriend Chelsea Kane on a date out in Hollywood. The couple have been fighting their busy schedules to spend more time together. Chelsea is appearing in the current season of Dancing with The Stars and Stephen who co-stars on One Tree Hill has also been filming a side project 'Wild Life. A New Generation of Wild with OTH co-star James Lafferty (Nathan).