Grace Hartigan (b. 1922) is one of the few remaining members of the generation transformed by Abstract Expressionism and, judging from the assurance and humor of her life work, she has enjoyed the experience more than most. If the canvases of her colleagues Pollock and de Kooning exude both liberation and tribulation, Ms. Hartigan’s radiate something more like a wholesome lyricism. Next to the paintings of Joan Mitchell — so grittily invested in a particular attack — Ms. Hartigan’s feel positively footloose. Currently on view at ACA, a survey of her work reflects the fascinating twists of a remarkably long and independent career.

Ms. Hartigan gained recognition early, exhibiting in a number of pivotal group shows in the ’50s, and soon saw her work acquired by major museums. She was the only woman to participate in the Museum of Modern Art’s “Twelve Americans” (1956) and the Europe-touring “The New American Paintings” (1958). Over the years, her on-and-off flirtations with representation and with idioms of Pop and the traditional masters attested to her free spirit, but they also placed her outside of the mainstream of second-generation Abstract Expressionism. This, plus her move to Baltimore in the ’60s, may account for the decline in her visibility in subsequent decades.

The selection of 30 paintings, watercolors, and collages at ACA spans half a century, with an emphasis on work produced after the mid-’80s. The loosely chronological hanging places the earliest canvases opposite the gallery entrance — a strategic move, as these tend to be the most vital works of the exhibition. A small, untitled canvas from 1951 features vivid, brushy swirls of earth colors, energetically set off against deep blue and off-white strokes. Each note of color, committed to canvas with let’s-see-what-happens verve, anticipates the next. The same palette, heightened to richer, deeper reds and yellows, animates the 7-foot-tall “Portrait of W” (1951-52). Here, hints of representation sneak in, with rhythms playfully suggesting a striding man.

Other early works include two large canvases from the mid-’60s, with the vital colors and racing black outlines that many of us think of as “classic” Hartigan. In the abstract “Male Image” (1966), vivid green-blues and gray-greens chase each other about the canvas, their velocities diverted by punctuations of pure cadmium red. One can read sexual connotations into various elements of the composition, but its intrigue lies in its vivacious self-absorption, rather than in messages of eroticism or exploitation. “The Suitor” (1967) offers the fragmentary details of a close-up rose blossom, with a more distant, schematized image of a dinner jacket; the connections between the two, across a field of arcing greens and yellows, convinces pictorially, if it does not strictly advance a clear narrative. On another wall, the collaged watercolor “Broken Hammer with Butterfly” (1972) shows Hartigan at the height of her funky rigor. Here, in a sinuous, dense composition of reds, blues, and paper-whites, hammers appear to bend before the onslaught of two butterflies.

Over the decades, Ms. Hartigan’s borrowings ranged ever wider, as she turned to cave paintings, images from coloring books, and such masters as Bronzino. “I Remember Lascaux” (1978), with its expansive circulation of four-legged creatures, combines the epic and the impromptu in striking fashion. Other investigations are more exuberant than perspicacious. “Bestiary” (1974), for instance, combines what appear to be pre-Columbian masks and medieval gargoyles in a fanciful design of earthy yellows and reds; though vigorous in technique, it suffers not so much from the discrepant motifs as from its indifferent pacing of forms.

Several canvases from the late 1980s reflect the artist’s ongoing dalliance with Pop art, a movement she once decried for its lack of emotion. These paintings depict the lightly drawn and sometimes smeared images of show-biz personalities beneath veils of droplets of paint. “Myopic Marilyn (Feathers)” (1989) occupies an intriguing limbo, not altogether resolved, between Ab-Ex’s expressive materiality and Pop’s generic sign-making.

A large number of paintings and watercolors from the mid-’90s demonstrate another tack: historical figures, painted in brightly colored arabesques on top of outline drawings of castles and battles scenes. Among these, the watercolor “Goldsmith” (1994) attains a somber radiance, the white of the paper vibrantly illuminating the pale notes of the figure’s face and brilliant red garment. In some instances, the multilayered recipe precludes the simple rigor of Matisse’s late work. “Napoleon” (1996), which appropriates details from a painting by Jacques-Louis David, is frankly silly; the splashy earnestness of the image of the emperor atop a rearing horse falls into an unfathomable gap between tribute and parody.

The most recent canvases at ACA show the artist barely missing a beat. Two paintings, both dated 2002, take inspiration from specific paintings by Watteau and Greuze. “Watteau’s Summer” shortchanges the French master, reducing his pictorial inventiveness to a broad piling of motifs: a goddess, a sickle, a lion. On the other hand, Ms. Hartigan’s free-form updating of the slick academic painter Greuze, who modeled his themes as suavely as his volumes, is gratifyingly appropriate. Sometimes there is justice, and Ms. Hartigan, ever true to her boisterous self, is the perfect artist to dispense it.

Until May 3 (529 W. 20th St., between Tenth and Eleventh avenues, 212-206-8080).