“20th Century Women” (A24) is such a major disappointment; it’s almost difficult to put it into words. In fact, it’s hard to believe that this chaotic mess is the work of writer/director Mike Mills, the man behind the Oscar-winning 2010 gay movie “Beginners.” Where that movie was effortlessly balanced and emotionally on the level, “20th Century Women” is sloppy, forced and unpleasant. It’s a complete waste of the talents of Annette Bening, on par with Ryan Murphy’s abysmal “Running With Scissors.”

Beginning with a car fire in a supermarket parking lot in 1979, “20th Century Women’s” main woman, Dorothea (Bening) is a single mother in her mid-50s raising a precocious 15-year-old son, Jamie (Lucas Jade Zumann). Smart but scattered, Dorothea is the very definition of an “unfit mother.”

Dorothea and Jamie share living space in a big house under constant renovation with boarders William (Billy Crudup) and Abbie (the eternally annoying Greta Gerwig). William appears to be in charge of the home renovations, as well as car maintenance, in exchange for room and board. Magenta-haired Abbie, who is dealing with a serious health issue, has ambitions to become a photographer. Self-absorbed Dorothea, who doesn’t feel like she’s capable of raising Jamie on her own, enlists Abbie, as well as Julie (Elle Fanning), a longtime friend of Jamie’s since childhood to assist her in the process.

For all its multitude of flaws, the places where 20th Century Women makes its most reliable statements are with music and literature. From the presence of revered feminist classics, including “Our Bodies, Ourselves,” to the Talking Heads’ “More Songs About Buildings” and other punk and new wave music of the time, the movie successfully makes noteworthy comments and observations about the impact of these cultural touchstones on personal and universal levels.

Anyone who saw “Beginners" knows what Mills is capable of doing. Here’s hoping that he can redeem himself with his next film project. Meanwhile, “20th Century Women” rates a D+.