Bam Margera has hit a fantastic milestone on his road to recovery ... we're told he's been sober for a month and is even hitting the skate park again.
Sources close to Bam tell TMZ ... Bam recently reached the 1-month mark and has been living on a farm owned by another professional skateboarder just outside of Philadelphia.
We're told he's been on the farm with his girlfriend, Dannii -- the 2 have been going to the gym every day and hiking with their dogs, and Bam's lost a ton of weight .