The adaptation of the best-selling novel also was nominated for best ensemble cast, along with the silent film "The Artist," the wedding comedy "Bridesmaids," the family drama "The Descendants" and the romantic fantasy "Midnight in Paris."
The nominations are among the first major honors on the long road to the Feb. 26 Academy Awards. The SAG list of contenders and Golden Globe nominees that will be announced Thursday help sort out favorites from also-rans for Oscar voters, whose nominations come out Jan. 24.
Davis is up for best actress and Spencer for supporting actress as black maids who agree to share stories of their tough lives with an aspiring white writer at the start of the civil-rights movement in 1960s Mississippi. Chastain also was nominated for supporting actress as Spencer's lonely, needy new boss.
"The Artist" ran second with three nominations, including a best-actor honor for Jean Dujardin as a silent star falling from grace amid the advent of talking pictures and supporting actress for Berenice Bejo, who plays a rising sound-era movie star.
Along with Davis, best-actress contenders are Glenn Close as a woman disguising herself as a male butler in 19th-century Ireland in "Albert Nobbs"; Meryl Streep as British Prime Minister Margaret Thatcher in "The Iron Lady"; Tilda Swinton as a grief-stricken woman coping with her son's horrible deeds in "We Need to Talk About Kevin"; and Michelle Williams as Marilyn Monroe in "My Week With Marilyn."
Joining Dujardin in the best-actor category are Demian Bichir as a hard-working illegal immigrant father in "A Better Life"; George Clooney as a neglectful dad tending his two daughters in "The Descendants"; Leonardo DiCaprio as FBI boss J. Edgar Hoover in "J. Edgar"; and Brad Pitt as Oakland A's general manager Billy Beane in "Moneyball."
"Albert Nobbs" star Close was a double nominee, picking up a best-actress honor for a TV drama series for "Damages." Close's co-star Janet McTeer was nominated for supporting actress as a cross-dressing laborer in "Albert Nobbs."
Overlooked for best actor was Gary Oldman, whose performance in the espionage saga "Tinker Tailor Soldier Spy" has been billed by critics as one of the best in his career.
Also snubbed was Michael Fassbender for his daring role in the sex-addict drama "Shame" and Ryan Gosling for two acclaimed performances in the action tale "Drive" and the political drama "The Ides of March."
Several Oscar best-picture prospects will sit out the SAG ceremony, including Steven Spielberg's "War Horse" and Martin Scorsese's "Hugo," but those are epic tales whose impact comes more from their scope than their performances.
Another Oscar potential that missed out at SAG was David Fincher's "The Girl With the Dragon Tattoo," which features a blistering break-out performance by Rooney Mara.
"Bridesmaids" was a rare mainstream comedy that has earned critical respect. Along with its ensemble nomination, the film earned a supporting-actress slot for Melissa McCarthy as a crude but caring member of the wedding.
Missing out in the supporting-actress category was Clooney's young "Descendants" co-star Shailene Woodley, who delivers a breakout performance as a troublesome teen.
Up for supporting actor are Kenneth Branagh as Laurence Olivier in "My Week With Marilyn"; Armie Hammer as Hoover's FBI colleague and soul mate in "J. Edgar"; Jonah Hill as an economics whiz kid in "Moneyball"; Nick Nolte as a bad dad trying to make amends in "Warrior"; and Christopher Plummer as an elderly, ailing father who announces he's gay in "Beginners."
Betty White, the guild's lifetime-achievement award winner two years ago, had two TV nominations: comedy-series actress for "Hot in Cleveland" and "Hallmark Hall of Fame: The Lost Valentine."
"Modern Family" led the TV side with five nominations, including best comedy ensemble and individual honors for Julie Bowen, Ty Burrell, Eric Stonestreet and Sofia Vergara.
SAG also honors unsung action players with a stunt ensemble prize. The film stunt contenders are "The Adjustment Bureau," "Cowboys & Aliens," "Harry Potter and the Deathly Hallows: Part 1," "Transformers: Dark of the Moon" and "X-Men: First Class."
TV stunt nominees are "Dexter," "Game of Thrones," "Southland," "Spartacus: Gods of the Arena" and "True Blood."
The 18th annual SAG Awards will be presented Jan. 29.