Chace Crawford -- Pot Case Dismissed!

Chace Crawford just won a big victory in a small Texas town, after a judge dismissed his marijuana possession case.

Chace was arrested in June, 2010 in Plano, Texas, after cops found an unlit joint in a car in which he was a passenger.

As TMZ first reported ... Chace cut a deal with prosecutors, in which the charge would be dismissed if he stayed clean for one year and performed community service.

We've learned the judge just dismissed the case, after Chace's lawyer presented evidence his client performed 80 hours of community service in Texas, working in a hospital and a church.