More than 700 singers, songwriters and industry officials attended Monday night's ceremony.
Green Day's "Boulevard of Broken Dreams" and "We Belong Together" written by Johnta Austin, Jermaine Dupri and Manuel Seal tied for the Song of the Year award.
EMI Music Publishing won Publisher of the Year for the fourth consecutive year -- racking up 17 hits in 2005 including "1985," "Behind These Hazel Eyes," "My Boo," "Shake It Off," "True," "We Belong Together" and "Yeah."
It was the second Songwriter of the Year award for 50 Cent, who led the pack with a total five awards. Other multiple award winners included Dupri, Sean Garrett, Ciara, Scott Storch, Johnta Austin, Ryan Cabrera, Destiny's Child, Michelle Williams, Dr. Dre, Alicia Keys, The Killers, Mike Elizondo, Ludacris, Maroon 5, Missy Elliott, Nelly, Gwen Stefani and The Game.
Britain's Annie Lennox was presented with the ASCAP Founders Award and U.S. punk rockers Green Day were given the ASCAP Creative Voice Award.
"Into the Sun" singer/songwriter Joseph Arthur received the 2006 ASCAP College Vanguard Award, which recognizes new and developing music genres.