There's a treat in store for anyone who thinks American art took a wrong turn after World War II, and for all those whose early ideas on art were shaped by the social-protest painters of the 1930s and early 1940s - or by the regionalists and American-scene painters of that same era.
This treat consists of over 60 outstanding examples of the art of that period grouped together at the ACA Galleries here under the title ''Social Art in America - 1930-1945.''
It's an occasion for nostalgia - and for reappraisal. Although quite a few of the paintings on view haven't survived the trip through time any too well, a surprising number of them have, and a few actually look better now than they did when first seen several decades ago.
I was most impressed by Jack Levine's wonderfully biting and incisive ''The Feast of Pure Reason'' (1937), William Gropper's ''The Last Cow'' (1937), Alexander Brook's haunting ''Georgia Jungle'' (which I saw as a child in 1939 after it had won first prize in the Carnegie International), John Steuart Curry's ''Hoover and the Flood'' (1940), Philip Evergood's ''Street Corner'' ( 1936), and Max Weber's ''The Toilers'' (1942).
And there were paintings by Benton, Bishop, Blanch, Hogue, Marsh, Shahn, and Raphael Soyer I also especially enjoyed.
While it is highly unlikely that history will decide any of these paintings are great art, it will have to admit that are remarkably authentic and powerful statements. Their integrity and quality cannot be denied - even in a time such as ours, which prefers to believe that these paintings and what they represent are pretty much beside the point of art.
The artists represented in this show believed that American art, in order to be good and true, had to spring from American themes, geography, history, folk tales, and issues. They felt any American art that didn't derive from this country's land and experience would lack heart and integrity and would end up as neo-European and superficially formalistic. So they turned their backs on international modernism - which is precisely what we cannot forgive them for today - and began to paint farms, workers, small-town activities, country landscapes, and urban life.
They also immersed themselves in social issues. It soon became impossible to attend any-sized exhibition without coming across paintings of overworked field or factory workers, mine disasters, sweat shops, corrupt bankers and politicians , strike breakers, vagrants, lynchings, and the effects of floods, famine, drought, and unemployment.
Even such artists as Reginald Marsh and Isabel Bishop, whose interests lay more in the direction of depicting human foibles and attitudes, found themselves reflecting this general mood of depression in their work. And such an unabashed modernist as Abraham Walkowitz found himself painting laborers in a style that resembled social-action posters much more than it did the art of the fauvists or cubists.
Almost everyone got into the act, even, of all people, the very young Jackson Pollock, whose murky and not very successful ''Cotton Pickers'' is included in this show.
In a strictly formal sense, color was one of the first victims of this trend toward social art. Paint manufacturers probably sold more tubes of burnt sienna, raw umber, black, and prussian blue during those 15 years than had been sold in the previous century. Almost everything was painted brown, even the grass, and, at times, bits of the sky.
Another victim was artistic professionalism, which declined somewhat during this period. Mediocrity generally went unopposed - as long as the artist painted Americana or American social issues and was obviously ''honest'' in his commitments.
Yet oddly enough a great deal of good came out of it all. I suspect, for one thing, that the solemn, moody, and almost deathly ''honest'' aspects of abstract-expressionism in its early days derived to a considerable extent from the spirit of the social art of this period. Both put character, identity, solemnity, and dedication before elegance, wit, charm, and formal innovation for its own sake. Underneath their stylistic and theoretic differences, Rothko, Kline, and Pollock were much closer in spirit to Benton, Curry, and Wood than they were to the American artists of more recent vintage. It is easy to imagine Curry and Kline enjoying each other, but the image of Kline and Warhol in deep conversation staggers the imagination.
More than that, the art itself was often remarkably good. Even those works that fail as art remain of great interest for their social content. Although this exhibition includes some prize examples of this art, it by no means exhausts the supply of good, solid work produced during this 15-year period - a fact that can easily be verified by visiting the various museums throughout the country, or by leafing through the art journals and art books of the period.
My only possible complaint about this exhibition is that space prevented the inclusion of some of the larger works of the regionalists - especially more of their studies and cartoons for murals, and a selection of their prints. But that's carping. One has two floors of interesting - and occasionally fascinating - things to look at as it is.
At the ACA Galleries through Nov. 28.