John Sloan (1871-1951), a leader of the Ashcan School, pioneered not so much a new style of painting as a new subject matter: the urban working class, depicted with unsentimental affection at work and play. Sloan lived his political beliefs, joining the Socialist party and drawing politically charged illustrations for such journals as the Masses, for which he also served as art editor. The power of his paintings, however, depends not on polemics but on frank depictions of ordinary people, captured in the everyday bustle of the streets and taverns and tenements of New York City. Today, to our more jaundiced eyes, the hopeful earnestness of these images belies a touching innocence, but Sloan’s technique seems as astute and vigorous as ever.

The intriguing exhibition, “John Sloan: An American View,” begins where the Ashcan School leaves off. This joint project of Gerald Peters and Kraushaar (which handles the artist’s estate) includes some two dozen paintings produced over the following quarter century, along with a number of Sloan’s etchings. The paintings reflect the influence of two key events: the Armory Show of 1913, which introduced American audiences to Fauvism and Cubism, and the beginning of Sloan’s lifelong habit of spending part of each year outside New York City, first in Gloucester, Mass. (1914-18), and then in Santa Fe, N.M. (1919-51).

Divided almost evenly between the two galleries’ spaces, the paintings reflect the artist’s heightened palette and concentration on portraiture, studies of nudes, and especially landscapes. Contrary to his prior practice of working in the studio, these landscapes were painted en plein air. At Gerald Peters, the striking “Fog on the Moors” (1914) shows Sloan more than ready for the challenge, both outlining and filling his forms with incisive hues and strokes reminiscent of van Gogh, though suffused by a subtler, mellower atmosphere. “Girl Seated, Chin on Hand” (1917) shows a similar blend of vigor and sensitivity, with royal purplish-blues and deep maroons and greens setting off the exuberant orange-pinks of skin. Again, Sloan both draws and fills with color, and the result is a brisk portrait of a young woman’s boredom, with the head and a supporting hand turning in pert opposition above the surprisingly abrupt vertical of an arm.

Two blocks away at Kraushaar, several equally vigorous landscapes from 1915-16 are accompanied by two later studies of nudes that stand out for their vitality of observation. In the small “Nude on Red Velvet” (c. 1920), the scissoring legs of the model’s pose neatly echo the butterfly shape of a sagging pillow. “Girl Undressing (Stockings)” (1927) shows Sloan at his best, somehow preserving the radiance of the figure’s skin tones within the competing environment of a colorfully furnished apartment. In this seemingly modest work, the artist’s diligence and enthusiasm seem in perfect accord, producing an image neither fussy nor perfunctory.

This cohering energy slackens in some of the later paintings. The hills in “Range, East from Sante Fe” (1940) at Kraushaar disport themselves in handsome but rather placid tiers. (By comparison, in “Mesa, Carson Reserve” from 1925, at Gerald Peters, Sloan captures the crisp facets of a peak and the mirroring line of trees with stroke-by-stroke alacrity.) Two images of nudes at Gerald Peters, dated 1928 and 1930, are competent but studied, as if the artist found no moment of modeling more urgent than any other.

A number of etchings, several of them dating to his Ashcan period, hang in both galleries. These are a treat; deprived of his seductive color, Sloan shows the rigor of his tones and contours. At Kraushaar, the very early “Schuylkill River” (1894) employs relatively few marks to expansively re-create an impression of spreading water, weighty hulls, and masts extending into open sky. At both galleries, multiple-figure genre scenes dating from the first decade of the 1900s set off rich darks and paper-whites in beautiful evocations of light; with these, Sloan lends a lustrous purposefulness to the casual preoccupations of museumgoers and apartment dwellers. Though less dramatic in atmosphere, “Knees and Aborigines” (1927) at Kraushaar wittily contrasts the garments of tourists and Native Americans. Later etchings in both installations impress for their technique. but tend to be more attentive than inventive in their descriptions of forms.

If Sloan’s Ashcan paintings demonstrate his empathy for a social class, his subsequent paintings show his affection for specific motifs: a model’s attitude, or a particular landscape. His partiality for the countryside seems to have been there all along, judging from an early, tiny landscape in a room of paintings by various Ashcan artists at Gerald Peters. “Country Road” (1908) evinces no preconceptions or composition or habits of design. It seems almost unshaped by experience or influence. Yet it catches, in confident impulses of color, the brilliance of a red cart on a sun-warmed road — testimony to the powers of an avid eye and a generous temperament.

Until May 30 (Kraushaar, 74 E. 79th St., between Madison and Park avenues, 212-288-2558; Gerald Peters, 24 E. 78th St., between Fifth and Madison avenues, 212-628-9760).