ART : Exemplary Contemporary : Commentary: The Museum of Contemporary Art has perhaps the finest collection of post-World War II art in the country. At long last, it is finding the space to show it.

Seeing the “greatest hits” in the Museum of Contemporary Art’s permanent collection always takes me by surprise. It isn’t just that a great work of art is a bottomless well, from which refreshing gulps can be taken again and again, or that so young a museum as MOCA claims an inordinate number of such deep swallows. Instead, I’m repeatedly startled that they’re at the museum at all.

Why? Because presenting the collection to the public has never seemed a high priority.

An ambitious program of temporary exhibitions has been offered by the museum since it was launched 12 years ago this month. During that brief life, MOCA has also managed to assemble a permanent collection of unusual distinction. In fact, of American museums principally committed to art produced after World War II, none can claim a more important collection or a more enterprising exhibition program than MOCA.

Oddly for a museum, though, MOCA has always seemed to consider the permanent collection to be of secondary importance to the program of temporary shows. MOCA has sometimes even seemed to be more kunsthalle than museum. A museum collects, but a kunsthalle , or public art gallery, doesn’t. It presents a roster of changing exhibitions.

MOCA has certainly been aggressive in acquiring significant works of art by classic figures of the postwar years, and it has made a point to gather work by young and newly emerging artists too. Visiting the museum, however, you could never be sure whether the great works in the collection would be installed for public view or whether they would be languishing in storage in order to make room for another traveling show.

Since a museum’s collection is indisputably its anchor, giving substance and presence to any temporal activity it undertakes, MOCA’s now-you-see-it, now-you-don’t way with its holdings sometimes made the place seem lightweight and ephemeral. MOCA undercut its own success.

Now, however, change seems to be afoot. Three weeks ago, at the reopening of the Temporary Contemporary, MOCA’s beautiful warehouse space in Little Tokyo, the museum unveiled an extensive selection of its major paintings, sculptures, drawings and photographs, focusing principally on American art from the 1940s to the 1970s.

For the first time, MOCA has made a significant commitment to permanent gallery space for its permanent collection. And more is on the way. Space has also been designated for that purpose at the main building at California Plaza.

Chief curator Paul Schimmel says the smaller of the two adjoining warehous es that make up the TC will henceforth be given over to display of the permanent collection. At California Plaza, works from the collection will be installed in the north galleries, starting next summer, in a suite of flexible, beautifully proportioned, light-filled rooms originally designed for that purpose by the building’s architect, Arata Isozaki. With 18,000 square feet at the TC and 8,000 square feet on Bunker Hill, MOCA has earmarked fully one-third of its exhibition space for full-time display of its remarkable collection.

One limitation of the industrially handsome TC space, with its uninsulated walls, wooden ceiling and clerestory windows, is that its temperature and humidity controls do not meet museum conservation standards. (To upgrade climate controls would cost, by some estimates, about $4 million, with a commensurate rise in annual operating costs.) The permanent collection therefore cannot be permanently installed; selections must be rotated, which MOCA plans to do every nine to 12 months.

Next summer, the TC will be reinstalled with works made in Southern California, either by artists who are based in L.A. or those who have worked here in the past. The selection will be made by curator Kerry Brougher.

No technical obstacles limit the Isozaki building at California Plaza. Next summer, Schimmel plans to install a relatively stable “core collection” of about 60 paintings and sculptures there. The work will focus on the 1940s, 1950s and 1960s, including exceptional paintings and sculptures by Jackson Pollock, Mark Rothko, Sam Francis, Alberto Giacometti, Lee Krasner, Jasper Johns, Robert Rauschenberg, Andy Warhol, Roy Lichtenstein, Edward Ruscha, Robert Irwin and other major artists of the period.

Many of those magnificent objects currently grace the TC, in a presentation of 167 paintings, sculptures, drawings and photographs that span the years 1939 (Piet Mondrian’s exquisite “Composition in Red, Blue, Yellow”) to 1980 (Agnes Martin’s spare, barely there abstraction and Richard Artschwager’s incongruous, eye-scratching image of an imploding building). The installation is called “Images of an Era,” and three-quarters of the works date from the end of World War II to the 1960s.

This emphasis on early postwar art is significant, because it records the unexpected march toward a cataclysmic moment in the early 1960s when, suddenly, American art changed everything. You can start by looking into the vivifying, slightly ominous, apocalyptically tangled skeins of dripped paint in Jackson Pollock’s small mural “Number One” (1949) and see the spectacular bridge he built from European Modernism to a highly personal, distinctly American experience writ large.

Then, go a few rooms down and see Edward Ruscha’s “Annie, Poured From Maple Syrup” (1966). Floating in space, the famous graphic typeface for beloved comic-strip waif Little Orphan Annie is painted in an illusion of pancake syrup. Pollock’s extraordinary New York School achievement is both exalted and upended by Los Angeles-based Ruscha, whose own sublime version of an American drip painting has left any memory of Europe far behind.

Ruscha’s “Annie, Poured From Maple Syrup” is one of several works on long-term loan to MOCA from the Norton Simon Museum in Pasadena. Others include 56 painted Brillo boxes by Andy Warhol--a witty song of praise to democratic ideals, here in the form of a pyramid of soapboxes from which the artist speaks his piece--and a wonderful 1967 collage by Wallace Berman, whose work remains among the few successful uses of a photocopying machine to make significant art.

Also on view, and for the first time, are extraordinary selections from MOCA’s recent acquisition of 2,100 photographs from the Freidus Collection. It’s unusual to integrate photographs with paintings and sculptures in a museum collection, but MOCA has successfully tried it before. It works wonderfully here too.

Between Pollock’s mural and Ruscha’s sign, make a stop at the two dozen restless photographs from Robert Frank’s epochal suite “The Americans” (1955-56), which dates from about midway between the paintings. Frank’s edgy black-and-white documentary pictures of life across the United States help make sense of Pollock’s and Ruscha’s paintings, as their paintings do his photographs.

Another exhilarating surprise is a group of 13 drawings, promised to MOCA’s collection from the Marcia Simon Weisman Foundation. An astonishingly high level of quality is sustained almost throughout, including exceptional examples by Willem de Kooning, Barnett Newman, Rothko and Robert Smithson. Some, like the De Kooning and the Newman, help fill collection gaps; others, like the Rothko and the Smithson, add another dimension to the collection’s paintings and sculpture by those artists.

‘Images of an Era” is installed in a handsome series of 15 galleries, washed with natural light. A very loose chronology is followed, more by ism than by year. A standard sequence of Abstract Expressionism, Color Field painting, Pop and Minimalism is laid out, and, where possible, multiple works by a single artist are included.

At the entrance, an unusual reading room provides books and catalogues that refer to artists in the collection. What makes the reading room unusual is that it is designed to mimic the living room and patio of an ordinary ranch-style house in Southern California, circa 1950. This seemingly quirky environment--created by BAU Design and furnished with appropriate sofas, chairs, tables and knickknacks--is in fact a cousin to that old-fashioned art museum staple, the period room. This one is simply much newer--and usable.

In place of 18th-Century French Rococo decorations or 17th-Century Spanish Colonial paintings, a dreamy Surrealist painting by Joan Miro hangs over the modern sofa, while Mondrian’s great, gridded abstraction adorns a side wall near the fireplace. Out on the “patio,” Giacometti’s towering bronze women and David Smith’s figure-like stack of polished steel boxes stand guard.

Incorporating actual art, this usable period room unobtrusively makes a didactic point about what you’ll see in the galleries. Museum collections typically begin their journey to public life as works of art acquired by private collectors who live with them at home. The permanent collection galleries of the Museum of Modern Art in New York have always been likened to Manhattan-size apartments, whose occupants richly patronized the museum, so it’s appropriate for MOCA’s warehouse entry to recall a suburban living room.

Reading rooms are one of two now-standard museum devices for providing context for works of art. The other is the ubiquitous timeline, which lays out topical events in social, political, scientific and cultural life. Happily, the timeline for “Images of an Era” is tucked into four small alcoves separating main galleries, where it doesn’t get in the way of the art.

Reading it, you might be mildly surprised to learn of William de Kooning’s first gallery show and Louis Bun~uel’s movie “Belle de Jour.” But I guarantee shock will overtake you upon discovery that in 1954 Sen. Eugene McCarthy was censured by his colleagues for inappropriate investigative activities.

Or maybe not. By then you will have already perused the introduction, in which MOCA haplessly apologizes for the “racism, sexism and class divisions” represented in the overwhelming predominance of work by middle-class white men you’re about to see. (Nationalism is apparently OK, since most of the artists are American; maybe that explains the Anglicizing of Dutch and Spanish given names.)

My advice is to groan, spend two seconds wondering why MOCA isn’t courageous enough to leave the collection in storage if it truly believes the issue to be so debilitating, and then move on to the galleries. There is astonishing art to be seen. The Museum of Contemporary Art has taken an important step in committing gallery space to its magnificent collection, and--timeline or not--it isn’t hiding its light under a bushel anymore.

* “Images of an Era: Selections From the Permanent Collection,” MOCA at the Temporary Contemporary, 152 N. Central Ave. Through June 23. Tuesdays-Sundays, 11 a.m.-5 p.m.; Thursdays, 11 a.m.-8 p.m. Adults, $6; students with ID and senior citizens, $4; children under 12, free; admission is free every Thursday, 5-8 p.m. (213) 626-6222.

* Chief curator Paul Schimmel will give a talk on the permanent collection on Thursday at 6:30 p.m.