SAN DIEGO (JTA) – What do you get when you bring together 5,000 of the Reform movement’s faithful for a conference in sunny San Diego in mid-December?

Four days of singing, learning, schmoozing and worrying at a gathering that seemed equal parts pep rally and intervention session.

For pep, there were the spirited prayer services, the morning-till-night stream of musical performances and Rabbi Rick Jacobs, the president of the Union for Reform Judaism, or URJ, who compared the challenges facing the movement to giant waves, crying “Surf’s up!”

“Big waves require more skill and courage to ride, but if ridden artfully they enable us to go faster and further than ever before,” Jacobs said, a giant screen projecting a swell behind him.

For the intervention, there was session after session devoted to the challenges facing the movement, especially the question of how to engage young adult Jews who, by and large, are steering clear of Reform synagogues.

“I think the Reform movement needs to remember that no matter how much we double down on great programming, it might not increase the likelihood that those young people are going to walk in,” Rabbi B. Elka Abrahamson, a Reform rabbi who is president of the Wexner Foundation, said in a conference session focused on the recent Pew Research Center survey of U.S. Jewry. “I think that’s really hard for this gathering to keep in mind because we are the people who love what we do, and we just think if we do more of it and do it better and do it more often and do it faster that they’re going to come.”

Though Reform is the largest denomination in American Jewish life, there was palpable concern at the conference that the movement is headed for a diminished future. The fastest-growing group in American Jewry is Jews of no religion, and the denomination doing best at holding its own is Orthodox, according to the Pew survey.

Reform membership is dwindling, synagogues are struggling to secure their bottom lines and, as Jacobs noted at the last biennial, 80 percent of Reform Jews are “out the door” by the end of high school. Many never return: Fewer than half of Reform parents have their children enrolled in some kind of Jewish youth, camp or educational program, the Pew survey showed.

Jacobs has promised to “reboot” the movement, and he is focusing his efforts on young people.

In his Dec. 12 biennial speech, Jacobs pushed for Reform communities to practice “audacious hospitality” by being as welcoming as possible to intermarried families and unengaged Jews; announced that URJ had just sold half of its office space in Manhattan and was investing $1 million from the proceeds to reshape its youth engagement strategies; and detailed the ways the union was making youth engagement a priority, including expanding Reform summer camps and NFTY, the National Federation of Temple Youth.

“Trends are a wake-up call, not our destiny,” Jacobs said, noting that a shrinking Reform movement helped reverse its decline in the 1930s by repositioning itself to be more open to traditional Jewish practice and Zionism.

“We adjusted our concept of who we are and what was needed to strengthen Jewish life,” he said. “We must be as open to reinventing ourselves today as in the past.”

At session after session, the talk was about how to reinvent synagogues, the central pillar of Reform Jewish life.

“My 20-year-old son wouldn’t be caught dead doing anything our synagogue does,” one audience member announced in a session on North America’s top models of engaging Jews in their 20s and 30s.

But the variegated dynamism on display at the biennial also belied the demographic challenges of a religious movement whose median age is 54 and only 17 percent of whose members, according to Pew, say they attend synagogue services at least once a month.

The five morning services offered at the biennial ranged from “Yoga Shalom: A Shacharit Embodiment of Prayer” to a visual service with no prayerbook to an Israeli-led service integrating prayer with pop music and poetry. Plenty of kippot were in evidence, sported by both men and women.

The virtual smorgasbord of conference sessions offered up to 33 concurrent options at some points. Participants could hop from “The Synagogue as a Center of Health and Wellness” to “Meaningful Routes to Involvement with Israel” to “Clergy Retirement: Preparing for Congregational Transition.”

On Saturday morning, Jacobs teamed with Cantor Angela Buchdahl of New York’s Central Synagogue to lead a Shabbat service replete with singing, dancing, interludes of reflective prose and “Storahtelling,” showcasing how far the movement has moved away from the Germanic, High Church-style Reform that was popular in the mid-20th century.

When they reached the Shema, Jacobs clutched the purple tallis he had made from fabric he purchased in Darfur and, as he grasped each tzitzit fringe, talked about how it symbolized people from the four corners of the earth — from Rio de Janeiro to Gedera, Israel, to the people suffering in Syria and the families of Newtown, Conn.

As Buchdahl strummed her guitar and masses of congregants broke into dance, Jacobs swayed and bobbed his head to the music.

Biennial organizers also invited several Jewish leaders from outside the movement to share their ideas for revitalization, including Rabbi Sharon Brous, a Conservative rabbi who heads the popular nondenominational IKAR community in Los Angeles; Ron Wolfson, a professor of education at American Jewish University; and Rabbi Donniel Hartman, an Orthodox rabbi who leads the Shalom Hartman Institute and accepted an award from the URJ honoring his late father, David Hartman, also an Orthodox rabbi.

Absent from the conference was any representative from the other major force in Jewish life focused on outreach, the Chabad-Lubavitch movement, though it was the subject of some curiosity, envy and anxiety at the biennial. Many spoke of their struggles competing with Chabad for adherents, asking how their cash-strapped synagogues can compete with Chabad’s free or lower-cost offerings.

At one session on engaging Israelis in America, Rabbi Meir Azari, executive director of the Daniel Centers for Progressive Judaism in Israel, warned, “If you don’t adopt Israelis, Chabad will be very happy to adopt them.”

At a clergy luncheon, rabbis peppered Jacobs with questions about his recent experience at the Chabad conference of emissaries, or shluchim, and his meeting with Chabad leader Rabbi Yehuda Krinsky. Jacobs also talked about Chabad in his keynote address.

“I believe with the very fiber of my being that young Jews are hungry, but not for a Judaism frozen in a distant time, no matter how loving and warm the purveyors — including Chabad, in particular — might be,” he said.

While trying to reshape the movement, the URJ is also trying to transform its own organization. The chairman of URJ’s board, Steve Sacks, acknowledged that the financing system “needs significant overhaul.”

Aside from downsizing its headquarters, Sacks promised a review of URJ policies on synagogue dues; a “simpler, fairer and more predictable” dues payment system; and a reduction in synagogue dues as a percentage of congregational budgets.

The goal, Sacks said, is to increase revenue to the movement through outside funding, including several new partnerships.

The Ruderman Family Foundation, which focuses on disabled people, is committing $600,000 over the next three years to help make Reform synagogues more disabled-friendly. And the Harold Grinspoon Foundation is offering URJ congregations up to $900,000 in support over the next five years to help bring PJ Library — a Grinspoon program that delivers free Jewish-themed books every month to more than 126,000 families — to small communities that don’t have it.

The URJ already has funding from the Jim Joseph Foundation, the Marcus Foundation and the Crown Family Philanthropies.

The union also is strengthening its relationship with the Hebrew Union College-Jewish Institute of Religion, the movement’s rabbinical school and academic center, in part by moving most of the URJ youth-programming professionals to the HUC campus in Manhattan.

“The biggest challenges of Jewish life,” Jacobs said, “cannot be tackled separately but must be faced together.”