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If you want to know where the future of Judaism in America is heading, pick up “The Jew Within” and prepare to be disturbed if not shocked.

“The Jew Within: Self, Family and Community in America” is a thoughtful canvass of contemporary attitudes about identity and continuity co-authored by Steven Cohen of Hebrew University and Arnold Eisen of Stanford. More than anything, it reminds us that our American Jewish community continues to reinterpret and reinvent itself to accommodate contemporary times and circumstances.

The authors believe we are experiencing another paradigm shift in the patterns and meanings of Jewish identity and activity. Soaring intermarriage rates, rampant assimilation and diminishing population have driven American Jews to re-examine the premises upon which their parents and grandparents (or even they themselves in earlier decades) lived their Jewish lives.

With personal and anecdotal data furnished by more than 60 interviews of mostly baby boomer Jews in America and in Israel, a pattern of discovery and transformation emerges that is sobering if not startling.

“Jews have moved away from the organizations, institutions and causes that used to anchor identity and shape behavior … The discovery and construction of meaning in contemporary America occurs primarily in the private sphere.”

Unlike their parents, boomer Jews make observance of the holidays the primary expression of their Jewish identification; synagogue affiliation is a distant second.

The far-reaching consequences of this finding for Jewish life become apparent as the testimony from the interviews accumulates.

More and more of Jewish communal life is now located in the private life, a preoccupation with self and family. “Today’s Jews, like their peers in other religious traditions, have turned inward in their search for meaning.”

This will be a difficult conclusion for many Jews, primarily older Jews, to accept. They took satisfaction in the relative stability, constancy and predictability of their Jewish lives — attending synagogue, observing or not observing kashrut, supporting Israel, celebrating bar and bat mitzvah, marriage under the chuppah and affiliating with Jewish organizations.

Today’s communal territory requires a new map. The milestones may still exist in familiar venues, but they have a different, more selective power. Jewish identity and continuity are constructed out of personal, private and individualized sources, such as one’s moral and ethical convictions.

The interviews in the book confirm that a very large number of Jews are departing for a new destination, a place where each person is the ultimate arbiter of what he or she believes and practices.

This carries echoes of the Jewish Renewal movement and post-denominational Judaism. Many young families joining synagogues are less concerned with identifying as Reform or Conservative or Reconstructionist than they are with aligning themselves as Renewal and secular. They consider themselves, according to recent demographic studies, to be Jewish but not in any of the mainstream or community meanings.

Perhaps the biggest surprise in the study is the extent to which younger Jews are selecting from various elements of Jewish tradition and incorporating these into their own Jewish lives. For example, the authors examine the role of family as traditionally the most important single source of Jewish identity.

However, while reaction to parental influence is generally equivocal, “childhood relations with grandparents were consistently recalled by our subjects as key positive influences upon their later adult decisions on behalf of more active Jewishness.” The chapters, rich in anecdotal detail, further develop the authors’ premise that the meaning of Judaism in America transpires within the self.

But decisions about ritual observance, affiliation with institutions and support of causes are vulnerable to change on a year-by-year or even week-by-week basis. The core community constituency that was in an earlier era taken for granted is literally fading from the scene; meaning that previously emerged from community now transpires within and is reflected externally by the self.

“The Jew Within: Self, Family and Community in America” by Steven M. Cohen and Arnold M. Eisen (242 pages, Indiana University Press, $27.95).