''The Private High School Today'' is a short (124 pages) paperbound study of just what its title says, with two additional features: A comparison of the data it is based on with a parallel study of the public high school today; and a series of analytical essays on what the data seem to show.
There are three interesting things about the study, however, that have nothing to do with what is in it.
* It is surprising that the study appears at all - given the educational research community's curious inattention to private schools.
* Two months after its appearance, the study was eclipsed by the more comprehensive, more thorough, more controversial, and more speculative report of James Coleman on the differences between public and private schools in the 10 -year retrospective study entitled ''High School and Beyond.'' (Editor's note: Dr. Coleman has since admitted that his private school statistics come from too small a sample to be ''significant,'' but that he could generalize about differences between public and parochial Roman Catholic high schools.)
* ''The Private High School Today'' represents an unparalleled cooperative effort among three presumed natural enemies: the private school establishment, the nine-times bigger public school establishment, and the National Institute of Education, a federal education research agency.
These three apparently peripheral points are interesting because they are symptomatic of a surprising happening - private education is hot!
It is hot because more parents, especially lower income and minority parents are choosing it for their children.
It is hot because new research seems to show that private schools do a better job than public schools.
And it is hot because President Ronald Reagan and a large number of congressmen think private school families should be assisted financially by a tax break (tuition tax credits).
It's not clear just why these developments should have all converged at once or just how they connect. But there is clear evidence of growing interest in private schooling.
One researcher, Donald A. Erickson, pointed out as long ago as 1971, in a study of 74 low-income Chicago area communities, that pupils in Roman Catholic parochial schools gained more in reading and math between grades 3 and 6 than did their counterparts in the public schools. He also noted that the cost per student in the private schools was 60 percent of the public school costs.
Ten years later Coleman reached similar conclusions. He suggests that private school students learn better because their teachers spend more time with them, they are given more homework, and more is expected of them.
A new study by Erickson comparing private and public schools in British Columbia also emphasizes dramatically the importance of a positive ''social climate,'' as a precondition to good student learning and achievement.
In the study of inner-city London schools (''Fifteen Thousand Hours,'' by Rutter, et al.), the conclusion is reached that two key elements for effective learning are general school climate and strong leadership.
So, there is increasing clarity from the research on what factors make for effective schools whether they are public or private.
The most important finding in ''The Private High School Today'' may be the suggestion that private school principals have more control and authority than their public school counterparts.
The most important line may be the last one in the book, by Denis Doyle, who is speaking of the swing in public interest toward excellence in education represented by private schools. Doyle concludes: ''Public schools ignore it at their peril.''
The reason for the sudden interest in private schools, I would argue, is not tuition tax credits, but broad disillusion over public schools.
There is only one thing that will improve the situation: the improvement of public education itself.
And that will happen only when the courts, litigators, state departments of education, lawmakers, and policymakers realize they have whittled down effective management of public schools to a tiny patch of ground that makes strong leadership almost impossible.