Does so-and-so "look Jewish?"

If Gary A. Tobin has his way, Latinos, African-Americans, and Asian-Americans should qualify for a "yes" to that question.

Dr. Tobin, president of the San Francisco-based Institute for Jewish & Community Research, has completed a study that claims that 20 percent of the American Jewish community is racially or ethnically diverse.

He defines that as including Jews who are African-American, Asian-American, Latino, Sephardic (of Spanish and Portuguese descent), Middle Eastern and of mixed race.

Previous estimates, he said, put the size of this "minority within a minority" at 10 to 14 percent.

"No people has ever lived in more places in more times, spoken more languages, had more colors, and had more nationalities than Jews," said Dr. Tobin.

He conducted his study over four years with his wife, Diane, and fellow researcher Scott Rubin.

Overall, they identified 6 million Jews in America – considerably more than the 5.2 million identified in the 2000-01 National Jewish Population Survey, which is generally regarded as authoritative.

The difference, Dr. Tobin said, comes from his inclusion of people who identify themselves as "cultural" or "ethnic" Jews. These individuals might feel connected to ancestors who were Jewish. Or, they may simply say, "I feel Jewish," even if they are not religiously observant.

American Jewish identity is a fluid thing and should be measured as such, Dr. Tobin said.

Jewish tradition, however, offers a less fluid definition. To many Jews, a person is Jewish only if his or her mother (or for Reform Jews, either parent) is Jewish, or if that person has undergone a formal conversion. This means many authorities would not recognize some of those identified by Dr. Tobin as an authentic part of Jewish culture.

Even so, Dr. Tobin said that his findings illustrate a larger cultural trend. American Jews "are a microcosm of the racial, religious, and ethnic boundaries that are crossing in America."

It's a trend that Jewish cultural institutions are picking up on. A current exhibit at the Jewish Museum in New York features photographs that show the racial, social, and ethnic diversity of Jews in the United States today.

"Everybody knows and agrees that the American Jewish community is more diverse than once it was," said Jonathan D. Sarna, a Brandeis University professor who is the author of American Judaism: A History (Yale University Press, $35).

Among Dr. Tobin's findings:

•Ethnic minorities – including African-Americans, Latinos and Asian-Americans – constitute just over 7 percent of American Jews. Many live in long-established communities in large U.S. cities, where they have built distinctly ethnic institutions, such as synagogues.

•Latinos are reclaiming their Jewish roots in growing numbers. During the Spanish Inquisition, many Jews were forced to convert to Christianity. Five centuries later, their New World descendants are reconnecting with their Jewish heritage and embracing Jewish rituals. Originally called conversos for their conversion to Christianity, members of this community, which is concentrated in the Southwest, now prefer the term reversos to symbolize a return.

•Intermarriage and adoption account for a significant number of those who identify as Jewish. Particularly in the Reform movement, where children of either a Jewish man or woman are considered fully Jewish, outreach to intermarried couples has been on the rise. This outreach has been prompted in large part by concern among U.S. Jewish leaders over the high rate of marriage outside the faith. Since 1990, more than 40 percent of all American Jews have married non-Jews.

Dr. Tobin, who adopted an African-American baby and is raising him as a Jew, is among a growing number of Jews who adopt babies from other races.

•Sephardic Jews account for 10 percent of ethnically and racially diverse Jews in America. These Jews, whose name is based on the Hebrew word for Spain, trace their lineage to Spain, Portugal, North Africa or the Middle East. Their ancestors fled Spain and relocated to the Middle East, where they were absorbed into existing Jewish communities known as mizrahi, from the Hebrew word for eastern.

Of course, for all the diversity, the large majority of American Jews are "Ashkenazic," or descended from Eastern European communities. Scholars said these "typical" Jews in particular can benefit from a deeper understanding of Jewish history – from knowing that Jews are not a monolithic people, and never were.

"The diversity of the Jewish community, which is a historical diversity, has really been lost in America because there's been such an Ashkenazic domination of Jewish life," said Rabbi Angela Warnick Buchdahl, associate rabbi at Westchester Reform Temple in Scarsdale, N.Y.

Rabbi Buchdahl has first-hand experience. Born to a white Jewish father and a Korean Buddhist mother, she grew up in Tacoma, Wash. In 1999, she became the first Asian-American to graduate from Hebrew Union College-Jewish Institute of Religion, the Reform seminary with campuses in New York, Los Angeles, Cincinnati and Jerusalem.

She believes that understanding the multifarious journey of Jews through history is enriching.

"Judaism is revitalized and made new by it," she said. "That's what makes the Torah a living Torah, the many eyes that have looked at it."

Holly Lebowitz Rossi, a Boston-based freelance writer, can be reached through her Web site, www.hollyrossi.com.