The divorce papers, filed by both Anderson and Rock, cite "irreconcilable differences" as the reason for the split, US Weekly reported Tuesday.
The couple seems to be unsure of when they actually split, with Anderson's papers listing the date of separation as Nov. 21, while Rock's papers claim it was Nov. 26.
The 39-year-old Anderson and Rock, 35, (born Robert James Ritchie) held their marriage "celebration ceremony" aboard a yacht July 29, but formalized it in Los Angeles in a private ceremony at the Beverly Hills courthouse.
The couple also held weddings in Nashville, Tenn., and Detroit, Mich.; and the official court documents state the date of marriage as Aug. 3, 2006.
Anderson has just finished filming in Vancouver, British Columbia, for "Blonde and Blonder" with Denise Richards.
Richards told People magazine about her costar: "My thoughts are with her and her boys. Pam is a very strong woman and will get through this difficult time."