It was officially released to radio on February 11, 2008, although many rock stations in the United States added it to their rotations earlier.

"So Happy" debuted on Billboard's Mainstream Rock Tracks chart on February 9, 2008, and peaked at #2 on April 5, 2008.

The song needed only three weeks to become a top-10 hit on the Mainstream Rock chart, making it their fastest top-10 entry to date.

The song features Shinedown vocalist Brent Smith performing backing vocals.

The video features alternating cuts of the band performing on a mansion porch and Serinda Swan as a disgruntled girlfriend who murders her boyfriend, subsequently steals his property, forges his will, and eventually cleans the murder scene before leaving with a mischievous smile on her face.