At the end of this month my high school class is having its 40th reunion. I won't be there. I wasn't at our 30th, or at our 20th, or at our 10th. Though I will not be attending the event scheduled for the weekend of June 27 for reasons I will explain, the realization that 40 years have passed since last seeing most of my classmates is reason enough to reflect on our lives. Curiosity is the main reason you show up to these things. After all, these were people with whom you spent five days a week, for 10 months of the year, for four years, and some for as many as 13 years. What I am thinking about is the trajectory my life took not five years after high school, in comparison with the rest of my classmates, and some fundamental decisions I made long ago that account for my absence next month. I clearly remember Chicago of the late '60s, the homes and storefronts of my neighborhood, West Rogers Park (officially West Ridge), its distinctive Jewish smells, sounds and images; my public elementary school, Daniel Boone; my Hebrew school at Congregation K.I.N.S. and my Chicago public high school, Stephen Tyng Mather. Mather High School, which opened its doors in September 1959, was for its first 15 years noted, somewhat caustically, for its disproportionate number of Jewish students. While there was never an official statistic, a reasonable estimate is that throughout the 1960s about 75 percent of the student population was Jewish. Such a figure is not unique in the annals of American public schools. Many public elementary and high schools during the first half of the 20th century, particularly in New York and other Eastern cities, boasted student populations whose majority was Jewish. One need only think of Philip Roth's Weequahic High School or Bronx Science. But Chicago is not the East Coast, and in this respect Mather High School stood out. THE 1960S WAS the decade, as we know, during which many of the social norms and institutions we had taken for granted were transformed, in some cases seemingly overnight. Among the changes was the first unraveling of the American Jewish social fabric. American Jewish ethnicity, never more celebrated than during first half of the '60s, seemed to lose some traction as we merged with the 1970s. Whereas my classmates' parents had consciously relocated, seemingly en masse, from Lawndale on Chicago's West Side to West Rogers Park and Skokie after World War II, my peers, by and large, had no particular interest in marrying and settling down in the Chicago area's next Jewish neighborhood. Following the achievements of the civil rights movement, new opportunities opened to non-WASPs throughout America, in education, in the professions, in the corporate world and in housing, and Jewish baby boomers took full advantage. Lacking any survey data, I am left to form impressions from the bits and pieces of news, gossip really, that I have picked up over the years about my Jewish high school classmates, their whereabouts, careers and marriages - this last demographic not uncharacteristic of my generation. A significant number, around half is not inconceivable, married non-Jews at least once. In fact, they live without any practical attachment to Judaism. The claim that they practice Judaism "as they understand it" or "their way" is disingenuous when that is really a euphemism for nothing. They are Jews, but less demonstrably so than their parents. Much like the generations-removed offspring of America's Sephardi and German elite, they may already be more accurately described as Americans of Jewish descent. IT GOES without saying that the 1969 graduating class of Mather High School, which is to say its huge Jewish majority, also lives without Israel in their lives. I presume that my Jewish classmates were among the 78% of American Jews who helped elect Barack Obama. However, I doubt that their vote had anything to do with his position on Israel, and had everything to do with his being liberal and Afro-American. And I have little doubt that the majority of my Jewish classmates have never been to, and have no plans to ever visit Israel. My classmates' indifference to Israel at its most precarious hour is revealing. June 1967: Israel is literally fighting for its survival. The Mather Rangers, an almost all-Jewish varsity baseball team, is fighting for the Chicago City-Wide High School Championship. I have no recollection of any discussion that week, neither in nor out of class, about that historic Middle East war. I do have a number of memories related to the virtual pandemonium surrounding the less historic play-off games and ultimate Mather victory in Comiskey Park. I also remember Ora, my first contact with a real Israeli, who entered our sophomore class as a consequence of her parents relocating from Tel Aviv in the middle of the school year. I can only imagine the dread she experienced that June. I don't remember anyone relating to that either. Given the particular Jewish milieu of my high school class, it is understandable why my decision not only to become observant, but also to later move to Israel, was so outrageous. A comparison of my life then with my life now involves a journey of immeasurable distance. A feeling of alienation surrounds me as I stare at our class's reunion Web site. Not surprising was the failure of Judy, one of our reunion's organizers with whom I shared some dozen e-mails these past few months, and whom I had not seen nor spoken to since our graduation, to query me about my move to Israel and what living is like here. Would she have shown interest if I were living all these years in France or India? But this isn't about just me. It is about unrequited Jewish solidarity. If my impressions of them are accurate, I wonder to what extent my classmates represent the Jews of America. As was the case with all our previous reunions, the festivities begin Friday night and are scheduled throughout Shabbat, with the central repast taking place at a non-kosher restaurant. To be both fair and realistic, I fully recognize that Mather High School is not the Hebrew Theological College (i.e., Skokie yeshiva). I have absolutely no right to expect the reunion program of a Chicago public high school, regardless of its dominant Jewish complexion, to consider, let alone conform to, Jewish tradition. So, that is why, again, I am not going. Besides, where would I find good humous or what some of my classmates call "peeta bread"? The writer is a philanthropic consultant living in Efrat.