Walter and Patty Berglund have problems, big problems. He’s frustrated. She’s depressed. Their son, a high school junior, has just moved in with the trashy couple next door. (He’s sleeping with their daughter.)

Walter and Patty are the irresistibly disconsolate couple at the center of “Freedom,” Jonathan Franzen’s monumental tragicomedy of depressive love.

Like “The Corrections,” the novel that won Franzen the 2001 National Book Award, “Freedom” savors the horrors of the American family — the terrible things spouses do to each other and to their children, and the poisonous coldness with which their children take their revenge.

Patty, a one-time college basketball star estranged from her high-stress parents, has grown up into a stay-at-home mom with a little too much time on her hands. Walter, a straight-arrow Minnesota eager beaver bent on bettering the world, has spent years of married life trying, and failing, to make his depressed wife happy. Or happier.

Their daughter, Jessica, doesn’t seem too scarred, but their son, Joey, a budding entrepreneur trying to school himself in rapacity, has cultivated defenses against his mother’s toxic love so harsh as to be toxic themselves. A wild subplot involves his attempt to enrich himself as a shady subcontractor in the Iraq War.

Occasionally drifting onto the scene is Walter’s college roommate, Richard Katz, a surly rocker to whom Patty has a not quite, or not yet, disastrous history of attraction. One year he’s riding the top of the charts and blowing it all on drugs, the next he’s building roof decks.

Franzen writes about depression with the authority of someone who knows what he’s talking about: “He strongly disliked the person he’d just demonstrated afresh that he unfortunately was. And this, of course, was the simplest definition of depression that he knew of: strongly disliking yourself.”

Yet the net effect of all this glumness is the opposite of glum. It’s exhilarating. In quality the novel is approximately on a level with “The Great Gatsby,” and in readability it’s on a par with “Gone With the Wind,” which it more closely resembles in length. And it’s funnier than either one. (Among its myriad achievements is what may be the finest scene of toilet humor in an American novel.)

I admired “The Corrections” without much liking it. As I told anybody I could collar at the time, it bewildered me that an author would dedicate so much labor and brilliance to a novel so massive and leave out beauty. There’s something sour and ugly (which is not to say untrue) at the heart of that book that I still don’t like to think about.

Part of it had to do with Franzen’s predilection — a penchant I associate with lesser novelists like Tom Wolfe and T. Coraghessan Boyle — for impaling his characters on a sharp stick and watching them writhe. That’s changed. He still has some diabolical plans for his characters, but now he’s pulling for them. He’s stopped blaming them. “Freedom” could more accurately be titled “Forgiveness,” the great Shakespearean theme.

The reasons for the change aren’t hard to fathom. “The Corrections” was Franzen’s third novel, and during the years he was sweating over it he was an obscure talent who wasn’t getting any younger. Then “The Corrections” made him a household name, at least in households where books are read; and success has a way of mellowing one’s anger.

(I have a feeling that when Shakespeare was writing his immortal comedies of forgiveness, he wasn’t doing so badly, either.)

I do have quibbles. Once I finished I recognized that the plot was more schematic than it seemed while I was reading — but a structure this big needs a strong armature, and its imperceptibility to the reader is hardly a defect.

Also, though the title made increasing sense to me toward the end, my own feeling is that a novel that’s probably destined to be read 200 years from now deserves a less generic name.

“Freedom” is not only gripping and sidesplitting; it’s more moving than at first you think it could possibly turn out to be. I finished it certain that Walter and Patty, for all their ridiculousness, for all their bad and sometimes even hateful qualities, are about to join a very elite group of the best-loved screwed-up couples in American literature.