THE LAST TIME Erich Segal '58 got the urge to write at length about his alma mater, he produced Love Story, and Freshman Week hasn't been the same since.

Fifteen years later, it seems our favorite Yale professor of classics is out to change the face of fair Harvard's reunions as well. Try as he might, though, Segal just won't be accomplishing it with The Class, a fictional account of the exploits of his own class before and after June 12, 1958.

What he has accomplished is the production of 592 pages that read like an explication of a "Class Notes" section in Harvard Magazine--fascinating but not penetrating. What he hasn't done--and it's this that makes The Class so contrived--is allow for the possibility that one or two of his classmates enjoy what they do or are Heaven forbid, happily married.

This is not to say that Harvard affiliates and non-affiliates alike won't eat it up--its publication date is today and it's already climbing the bestseller lists--or that it has no redeeming value. Segal does more with his stereotypes than, say, Alice Adams '46, whose Superior Women, a tale of Radcliffe in the '40s and the havoc it wreaked later, all but announced its conclusion halfway through. There are a few surprises.

Coming from the man who, in Love Story, captured the Harvard of the early '60s right down to 'Cliffie bitchiness and the secular religion that is Crimson hockey, it's no surprise that the college portions of the novel ring true. The one problem here is that the period 1954-58 was not, to put it mildly, a time of campus unrest or even great social shakeups. Segal makes up for this with painstaking accounts of such bygone rigors as the Step Test and the Swim Test, while ignoring real campus news like the hockey heyday of Bob (really '58) and Bill ('56) Cleary (who did make it into Love Story).

But believable accounts of "life after college" in the novel-of-Harvard genre--chief among them Anton Myrer '44s. The Last Convertible--are almost absent from the late sections of Segal's magnum opus. As far a comparisons go, let it be said that Rona Jaffe '51 has a lock on the 25th Reunion trash novel category of this ilk, and Class Reunion wasn't anywhere near as pretentious as The Class, Even Love Story, while making no attempts at profundity (except, of course, in its one infamous and unfortunate definition of love), has its place in this venerable category of literature. Maybe Segal is just trying too hard.

EVEN BEFORE page one, the Harvard-centric nature of The Class is apparent, as Segal quotes William James on the joy of being a "son of Harvard," and notes that James received his M.D. (Harvard, of course) in 1869. Later, he also cites John Updike '54, Ralph Waldo Emerson '21 (1821, that is), e.e. cummings '15, ad nauseum. Most irritating, though, is his choice of members of the Class of 1958.

This is Harvard Diversity. Meet:

* Danny Rossi, The Musical Genius Who Sacrifices Everything To Go To Harvard;

* George Keller, The Eastern European Refugee Who Sacrifices Everything To Go To America;

* Theodore Lambros, The Townie Who Grew Up In The Shadow Of The Yard But Loves Harvard Anyway:

* Jason Gilbert, The Great Athlete Who's Ashamed Of Being Jewish;

* (And, lest we forget Oliver Barrett IV '64) Andrew Eliot, The Preppy With The Heart Of Gold.

A couple of these fictitious sons of Harvard--the token preppie's last name has necessitated a disclaimer in the "Publisher's Note" actually take less than, predictable paths, but not before a detour through a detail and cliche-loaded section about 1954-58. The details are sure to cause reminiscing in Harvard Clubs nationwide, if not in dorm rooms:

After the official registration, they had to run an endless gauntlet of wild, paper-waving proselytizers, all vociferously urging Harvard's now-official freshmen to join the Young Democrats, Republicans, Liberals, Conservatives mountain climbers, scuba divers, and so on...