The presidents of MIT, Princeton, and Stanford released a joint statement Thursday criticizing Harvard President Lawrence H. Summers’ suggestion that “innate differences” between the sexes account for the underrepresentation of women in science and engineering, while leaders of several other schools presented a series of proposals designed to make the faculty tenure process more “family-friendly.”

In their 700-word missive, Presidents Susan Hockfield of MIT, Shirley Tilghman of Princeton, and John Hennessy of Stanford stopped short of criticizing Summers directly, but said that much of the uproar generated by Summers’ controversial remarks last month “has had the untoward effect of shifting the focus of the debate to history rather than to the future.”

Although it called for “specific policies” that would “enable women with children to strike a sustainable balance between workplace and home,” the three chiefs' statement did not present any concrete policy proposals.

The statement surprised some who saw it as a breach of the etiquette of collegiality among university presidents.

But Summers this weekend backed his colleagues’ call for measures to encourage female scholars in the sciences.

“I strongly share their commitment, and as I’ve said in recent weeks, the primary issue is in meeting these challenges going forward,” Summers said through a spokeswoman.

HIGH-PROFILE PANEL REPORT

In a separate development Thursday, the National Panel of Presidents and Chancellors, comprising top administrators at 10 universities, offered a set of detailed recommendations aimed at making life inside the ivory tower more accommodating of professors with families.

The high-profile panel includes leaders of some of the nation’s most prestigious state colleges, including the Universities of Michigan and North Carolina, as well as Tufts President Lawrence S. Bacow, a 1976 graduate of the Kennedy School of Government (KSG) and Harvard Law School.

One of the report’s most innovative proposals urges schools to allow tenured and tenure-track professors to work part-time for up to five years while raising young children or caring for elderly dependents.

Under the proposal, junior faculty members who temporarily opted for part-time posts would not face penalties in the tenure review process.

The proposal for a part-time option “is really quite new” and has only been implemented at a handful of schools, according to Gloria D. Thomas, an American Council on Education official who served as project coordinator for the panel’s report.

The panel also said that assistant professors who reduce their research output or teaching load due to family responsibilities should get more time before facing tenure review—a policy known as “stopping the tenure clock.” Thomas wrote in an e-mail Saturday that the policy has produced “mixed results on campuses nationwide.”

Both male and female professors often decline to take advantage of family-friendly policies either “for fear of retribution” or out of concern “that they will be seen as less than serious scholars,” according to Harvard Graduate School of Education researcher Cathy A. Trower, who advised the panel of presidents.

A 2003 Penn State report found that nearly one-fifth of both male and female professors at colleges that allow faculty to stop the tenure clock did not take advantage of the policy after the birth of a new child, even though they recognized that it would have helped them in their academic careers.