Men and women together in class is as much a part of college life today as final exams and grade-point averages. Half a century ago, that wasn't the case at many elite colleges. Nancy Weiss Malkiel, professor emerita of history at Princeton University, documents the movement that ended single-sex education and the social changes it brought about in Keep the Damned Women Out: The Struggle for Coeducation (Princeton University Press; $35).