During the 1960s, The Jewish Museum was at the vanguard of the contemporary art world, mounting career-defining shows for artists like Jasper Johns and Robert Rauschenberg. In those days many in the emerging art world were Jews — artists like Mark Rothko and Diane Arbus, the dealer Leo Castelli, the critic Clement Greenberg (though not Rauschenberg and Johns) — and the museum made it its mission to champion their work.

But by 1971, the museum underwent a sea change. The board of trustees brought in a new director, Joy Ungerleider-Mayerson, they wanted to focus on the museum’s original mission, which since its founding in 1904, was to showcase the whole of Jewish history and culture, not just art. The museum had amassed a treasure trove of precious Judaica and archaeological artifacts from Israel and felt it should be highlighting those pieces instead.

So when yet another new director — Joan Rosenbaum, then a 38-year-old nonprofit museum administrator with a fine art background — was chosen in 1981, it was unclear what direction she would take the museum. “When I came in, there were many things going on,” said Rosenbaum, 67, who announced her retirement last week after 30 years at the helm.

But in short order she defined her mission, and the museum’s along with it. She would put equal emphasis on both fine art and Jewish history and culture. And perhaps most critically, she’d try to get the museum on par with the city’s premier art museums, including the Whitney and the Museum of Modern Art.

“By scale it’s small,” said Richard Armstrong, director of the Guggenheim Museum, which averages about five times as many visitors annually as The Jewish Museum’s 200,000. “It was a place I went to less frequently” during the 1970s, he added, “but when Joan got there, it became a necessity.”

Susan Talbott, director of the Wadsworth Atheneum Museum in Hartford, Conn., who has known Rosenbaum since the her days at the Whitney in the 1980s, echoed that sentiment: “All I can say is that The Jewish Museum was not on my radar screen in the seventies,” she said, “but it has been since Joan’s been there.”

Rosenbaum discussed her career in her spacious corner office in the museum’s Upper East Side home, which has doubled in size under her tenure.

She disagreed with the notion that she shifted the museum’s focus back to fine art when she arrived, saying instead that she only gave it an increased focus. After all, she noted, one of the first major projects she initiated was the expansion of the museum’s building. At its center would be a new permanent exhibit, “Culture and Continuity: The Jewish Journey,” which would tell the story of the Jewish people’s 4,000-year history.

The exhibit opened in tandem with the museum’s $60 million expansion in 1993. The fundraising campaign also provided the foundation with its endowment, which today stands at around $94 million, more than 50 percent larger than the Guggenheim’s $62 million.

“I thought the museum was very well positioned to present exhibitions that combined art and Jewish culture,” Rosenbaum said. “It took time for that to take hold, but I think that we succeeded.”

It’s hard to disagree. The museum now has an annual operating budget of about $15 million, compared to $1 million when she arrived. A seat on its board of trustees, which has 41 deep-pocketed members, compared to 26 when she arrived, has become a mark of distinction perhaps as never before.

Joshua Nash, the current chairman of the board of trustees, said that Rosenbaum has made an aggressive push to get younger patrons on the board in the last decade. Today about a third of its trustees are around 50 or younger. And many, like Nash, a 49-year-old investment firm executive, are encouraged to take prominent roles. “It’s normally very difficult for young people to assume leadership positions,” said Nash. “But it’s been something she’s spearheaded.”

When The Jewish Museum opens a new exhibit these days, it generates as much coverage, and at times controversy, as any major museum. A case in point is The Jewish Museum’s 2002 show “Mirroring Evil: Nazi Imagery/Recent Art,” which drew national coverage after several Holocaust survivors complained that it trivialized the Holocaust.

But Norman Kleeblatt, the show’s curator and now the museum’s chief curator, said that he and Rosenbaum knew the show might offend some viewers. Not long after Rosenbaum arrived, she instituted focus groups with potential audience members that would give feedback on every developing show idea.

Some Holocaust survivors focused on certain pieces, like Zyklon B gas canisters painted with Chanel logos, that seemed particularly offensive. But rather than simply pull those works out of the show entirely and risk further condemnation — like what the National Portrait Gallery in Washington did last week, removing a work by a gay artist (it featured ants on a crucifix) after the Catholic League deemed it offensive — Rosenbaum cut a compromise. She placed the most provocative pieces in a separate room and wrote wall texts warning viewers of the sensitive subject matter.

“It’s an incredible example of how a museum acts responsibly and doesn’t pull away from controversy,” said Steven Dubin, a professor of arts administration at the Teacher’s College at Columbia University and author of “Displays of Power,” a history of controversial art exhibits. He said he uses “Mirroring Evil” as a case study in how to respect the sensitivities of certain audiences without caving in to outside pressure.

Reflecting on that show, Rosenbaum said that the entire controversy might have been avoided had she not allowed a reporter to see the show’s catalogue months before the show opened. In an article, the reporter drew a comparison to the Brooklyn Museum’s “Sensation” exhibit, which spawned intense public scrutiny three years earlier. The difference was that by the time “Mirroring Evil” actually opened, the controversy had largely abated. Many critics panned the show as simply bad art, but few were morally outraged. And tellingly, no one protested.

Rosenbaum now says she has few regrets: “I am proud of that show,” she said. “I think people may have misunderstood what it was about. … It was about how young artists were responding to the imagery of the Holocaust” and not about the Holocaust itself.

But Rosenbaum’s most enduring legacy may be mounting challenging shows that question core issues of Jewish identity, without dumbing them down. Under her tenure, curators have consistently engaged the Holocaust and Israel, as well roles Jews have played in the arts, both highbrow and mainstream, in America and abroad.

When asked if she considers some of her shows populist, she said, “We always consider whether a show will be popular or not, but it doesn’t start that way. It really starts with a curator making a really good proposal, with good art and good objects to show, and a good story to tell.”

Rosenbaum has mounted popular family-oriented shows as well, but they tend to be buttressed by intellectually serious arguments: a show on Shrek, for instance, addressed the deeper psychological motivations of its creator, William Steig. And a recent show on Curious George detailed how its creators, German Jews living in Paris, escaped Nazi-occupied Europe and how that experience influenced the Curious George books.

Exhibits on artists like Man Ray and Amedeo Modigliani, the latter of which drew attendance records, have also led many to rethink the role artists’ Jewish backgrounds have played in their art. “For someone who’s not Jewish,” said Armstrong, the Guggenheim’s director, The Jewish Museum’s exhibits “add real dimension to my understanding of modern and contemporary art.”

Scholars have also benefited from another Rosenbaum initiative: catalogues that are co-published with Yale University Press. Many of them feature learned essays by academics that become fodder for future research. “The museum not only receives the scholarship of others, it actually generates it,” said Jenna Weissman Joselit, a prominent scholar of Jewish history, and the Charles E. Smith Professor of Judaic Studies and Professor of History at The George Washington University.

Weissman Joselit added that The Jewish Museum has also benefited from a fundamental shift in the nature of the American Jewish community. As Americans have become more secular and synagogues less visited, the museum has taken an increasingly important role in Jewish life. “The Jewish Museum has stepped into the breach,” she noted. “That might have happened anyway, but there’s no doubt that Joan was the right person at the right time.”

Rosenbaum acknowledges that all ethnic museums, The Jewish Museum included, have been helped by the broader interest in group identity that’s taken hold since the 1960s. But most new Jewish museums have centered that identity on either the Holocaust or the tale of American achievement. In the past two decades, for instance, the United States Holocaust Memorial Museum in Washington and the recently opened National Museum of American Jewish History in Philadelphia have been the most prominent additions.

Like those museums, Rosenbaum has engaged the central interests of her core community. But most agree that she’s done it by challenging basic assumptions and broadening conclusions. “It seems to me that very few museums get past the rah-rah phase,” said Dubin, of Columbia’s Teacher’s College. “For the most part, those [ethnic museums] are pretty damn boring. But the Jewish museum has gone well beyond the rah-rah phase that still many Jewish museums are in.” He went on, “It doesn’t need to prove itself anymore.”

When Rosenbaum announced her retirement last week, many within the art world, even her own institution, said they were surprised. But Rosenbaum leaves at time when younger Jewish museums are thriving. Across the country, Jewish museums are either growing or sprouting anew. Not only is there the new history museum in Philadelphia, but there is also the rebuilt Contemporary Jewish Museum in San Francisco. For some of these museums’ leaders, Rosenbaum has set a new standard.

“She’s really a role model for museum directors everywhere,” said Connie Wolf, the current director of the Contemporary Jewish Museum (CJM). Wolf, 51, said that when she became the CJM’s director 12 years ago, Rosenbaum told her she’d give any help she needed.

Rosenbaum’s been true to her word: since the CJM moved into its new Daniel Libeskind-designed building in 2008, The Jewish Museum has shipped many of its exhibits to San Francisco. That is critical for the CJM, whose new building has created high expectations, but which still lacks a permanent collection. “In the museum world, you have to have friends,” said Wolf, “and Joan’s been a very close one of mine.”

But Rosenbaum said that after 30 years, she felt it was simply time to move on. The Jewish Museum has hired a search firm that will work with its board of directors to pick a new director, who’ll be announced in the next six months, said Nash. And Rosenbaum will officially leave on the last day of June.

When asked if she has any vision for the museum in the years ahead, she said: “I leave that up to the new director to decide.” But, still vigorous and only 67, she says she is open to taking on another job somewhere else. As she put it: “I’m not ready to hang up my dancing shoes yet.”