Seann William Scott I'm Out of Rehab!

4/13/2011 1:45 PM PDT
After completing a 30-day stint in a treatment facility -- "American Pie" star Seann William Scott was back out in public last night ... taking in a Knicks basketball game in NYC.

Seann had voluntarily sought treatment for "health and personal issues" back in March -- and today a source connected with the actor tells us, "He completed the 30 days successfully ... he's doing great."

Reps for Seann confirm he will begin shooting for "American Pie 4" next month.