American Jews can breathe a collective sigh of relief. At least that appears to be the conclusion of a recent demographic study conducted by the Steinhardt Social Research Institute at Brandeis University.Released during this year’s Association for Jewish Studies conference in Boston on December 19-21, the SSRI found there are now 6.5 million Jews in America – a whole million more than estimated in previous surveys and studies.But it might be too early to celebrate. A North American Jewish Data Bank report released just weeks ago by the Hebrew University’s Sergio DellaPergola, together with Arnold Dashefsky of the University of Connecticut and Ira Sheskin of the University of Miami, contradicts the SSRI’s findings. DellaPergola et. al. estimate the number of American Jews in 2010 at only about 5,275,000. DellaPergola publicly contested the SSRI findings when they were presented in Boston by lead researcher Leonard Saxe, professor of Contemporary Jewish Studies at Brandeis University.It is not our job to determine who is right in this clash of the Jewish demography titans. But it does seem hard to believe, as the SSRI would have us do, that American Jewry is multiplying faster than the 9.7 percent growth rate of the general US population over the past decade.How could this occur at a time when over half of Jews intermarry and fertility rates are around 1.8 children per Jewish woman, lower than the 2.1 needed just to break even? Conversions to Judaism are not adding members to the tribe either, according to recent studies that show that there are more Jews leaving the faith than joining.As the US remains in the throes of a major economic downturn, meanwhile, Jewish immigration to America from Israel or elsewhere is looking increasingly less attractive.The Reform Movement’s decision in 1983 to recognize as Jews those born to a Jewish father even if the mother is not Jewish might be contributing somewhat to Jewish population growth. In the Boston area, for instance, over half of young people who define themselves as Jewish are the product of mixed marriages.But this phenomenon is probably restricted to cities like that one, which enjoy strong and affluent communities where it is attractive to be Jewish. Statistics show that the offspring of a mixed marriage are much more likely to ignore their Jewishness and to intermarry than those born to a Jewish couple. This is particularly the case when only the father is Jewish.Meanwhile, even when Jews do marry other Jews, they do so at a much later stage in life than in the past, which has a negative impact on fertility. One-third of American Jewish women and more than half of men aged 25 to 34 are unmarried. As Brandeis University professor Sylvia Barack Fishman has shown in her studies of young Jewish Americans, many are looking to “find themselves” before committing to marriage. Successdriven, young Jews are uneasy about giving up opportunities before defining their own path. Large networks of singles make single-hood normative.Debate over its actual numbers aside, American Jewry has been undergoing a demographic crisis for some time now. And that crisis will only worsen as Jews aged 65 or older, who represent 20% of American Jewry, and those slightly younger who are a product of the “baby boomer” era, gradually pass away.Thus the community should not be lulled into complacency by the SSRI report. Tremendous resources should continue to be devoted to fighting negative demographic trends. Strengthening Jewish identity is a lifetime endeavor. It starts at the cradle, with education and life-cycle events that give meaning to Jewishness.WE WOULD like to offer an additional bit of advice to American Jews: Visit Israel. A study conducted last year, also by Prof. Saxe, found that young Jews who have visited here in the past decade under the auspices of Taglit-Birthright, an organization that offers free 10-day trips to Israel, were 57% more likely to be married to a Jew than nonparticipants.And those who were still single were 46% more likely than nonparticipants to view marrying a Jewish person as “very important.”A visit to Israel, whether or not within the framework of Taglit, has the potential to strengthen Jewish identity. Amid all the talk about Diaspora-based alternatives to political Zionism and the decline of ethnic nationalism, and beyond all the debate over specific Israeli policies, there is no substitute for witnessing firsthand the return of the Jewish people to its historical homeland and its ongoing endeavor to build a state that is both Jewish and democratic.To experience the tremendous achievements, and to be awed by the challenges of sovereignty in this historic sliver of land – that adds up to a powerful incentive to care about staying Jewish.