Elizabeth Murray, whose 40-year retrospective recently opened at the Museum of Modern Art, began to be noticed in the later 1970s -- a strange, in-between moment in the history of painting. Rigorous, self-important abstraction was feeling very tired, but nothing had come along to take its place. Murray's paintings didn't try. They were about variety, and play, and anything that seemed to be the opposite of orderly and systematic abstract art.

Abstract painting was often said to be about flat forms on flat surfaces. So Murray made her pictures on the wackiest of shaped stretchers. They didn't only have eccentric outlines, they also often curled and writhed in three dimensions.

A mature artist was supposed to pick a single color scheme and explore the melodies and chords that it allowed. So Murray let her brush play everywhere across her palette, from turgid browns to Playskool pinks and yellows.

High modern art was serious and sober, with angst the feeling of choice. So Murray made her pictures look as goofy as could be. She borrowed comic-strip imagery: A tramp's oversize shoes; popping buttons; capital-O mouths and tiny i-dot eyes, stuck onto blobby, Silly Putty figures.

It looked as though she wanted her paintings to be silly, and even ugly, just to make sure they weren't merely clever and tasteful. Murray broke almost every rule for what made a painting count as a success. That made her pictures all the more successful.

Maybe the most important rule she broke was the one that said form and content should be inseparably bound.

The first impression this show gives -- maybe even the second and third -- is that Murray's art is all about good fun. That's what her wacky forms and colors seem to telegraph to us. That formal impression is so strong it can lead to a Charlie Chaplin double take, once you've finally absorbed her pictures' content.

A 1984 painting called "Can You Hear Me" at first seems like an explosion of cheery shapes in blue and red and green, with a comic little face stuck on top. Look closer and longer, however, and you realize that it's an image of someone in a panic, seen from above with arms outstretched and a scream erupting from an open mouth.

"What Is Love," from 1994, is a twisting canvas in the shape of a rubber-footed bed, in bright blues and yellows. A cartoon figure rests its head on a pink pillow -- and tears at the white sheets with its 10 misshapen fingers, its face contorted in pain.

In the past five years, Murray's pictures have seemed more and more cheery. "Bop" and "Bowtie" and "The Lowdown" and "Do the Dance" favor cotton-candy pinks and baby blues and absurd cherry reds. They're full of comical zigzags and balloon shapes and goofy action lines. They look like playpen busy boxes, full of stuff to keep a toddler occupied.

Look again.

Some of the blobs are figures, with bones and innards showing as though seen in an X-ray. An ominious red arrow prods at throbbing spot on one of them, and the victim doubles over in pain. A zipperlike row of X's, painted over a series of sausage shapes, might just be someone's guts, with Boris Karloff stitches in place. A green bottle pours a chemical-blue liquid onto a living cell; it looks like the cell may not be taking it well.

Murray's pictures are looking sprightlier than ever. They are also more harrowing.

The Elizabeth Murray retrospective is on view at the Museum of Modern Art, 11 W. 53rd St., New York, through Jan. 9. Call 212-708-9400 or visit www.moma.org.

Elizabeth Murray's "Bop," left, and "Sun and Moon" are part of MoMA's 40-year retrospective of the artist.