Coeducation is one of the least studied of all major topics in education. Researchers have attacked the issues of race and social class integration relentlessly. Likewise, the question of ability grouping (separate or mixed) has been investigated extensively. The pros and cons of mixed- and single-sex schooling, on the other hand, have received little attention.
Recently, however, a growing concern regarding the effects of coeducation for females has arisen. The critics of mixed-sex schools have focused primarily on British and Australian secondary schools [4, 19, 51, 61] and higher education in America [23, 24, 54, 57, 58]. In mixed-sex schools, critics argue that: (1) women's cognitive development may be depressed or impaired; (2) their educational and occupational aspirations and ultimate attainment may be lowered; (3) their self-confidence and self-esteem may be damaged; (4) they may receive unequal treatment in the classroom and in curriculum opportunities; (5) teachers may devalue the work of female students relative to males; (6) sex segregation is the existing norm in coeducational schools anyway [32, 41, 47].
Studies of Mixed- and Single-Gender Schooling
The available data suggest that single-sex schools may offer an educational advantage, especially for women [5, 11, 20, 25, 28, 41, 42, 43, 52, 54, 55, 56]. In addition, a number of experimental educational projects point toward the potential value of single-sex classes, especially for women in mathematics [12, 33]. Girls Clubs of America have continued to sustain a single-sex environment and continue to demonstrate success in a variety of areas, including science and mathematics training, general leadership, and the prevention of premarital pregnancy .
Of particular interest in the United States are the long-term effects of single- and mixed-sex colleges for women. Unlike primary and secondary schools, colleges and universities in America were largely single-sex institutions until the beginning of the twentieth century. In 1870 the majority of colleges and universities were for men only (59 percent). By 1930 the majority of schools were toed (69 percent) and there were an equal number of male and female single-sex institutions. Since 1960 the enrollments for both men's and women's colleges have declined considerably. Presently, however, the remaining women colleges may be enjoying "renewed vigor" [see 26, 50]. Yet, during 1991 only 92 women's colleges were operating, and by 1992 only 85 remain . With the exception of Mills College, which recently rescinded its decision to go coeducational , and Chatham College, which decided to remain single-sex after a year-long debate, the transformation of women's colleges into coeducational schools has been the persistent pattern for the past half century.
Yet, the effects of single- and mixed-sex colleges for women remains an unresolved empirical question. Some studies have shown that students attending women's colleges have higher career aspirations and achievements, lower drop-out rates, and are more likely to enter graduate or professional schools [5, 55, 56]. In a series of exhaustive studies covering a half-century period, Tidball  concluded that graduates of women's colleges were twice as likely as their counterpart graduates of coeducational colleges to have been cited in Who's Who of American Women [see also 40]. In later studies, Tidball reports similar findings favoring women's colleges with regard to the baccalaureate origins of American scientists and scholars  and entrants into American Medical Schools .
Despite this array of evidence, the move toward coeducation persists, and some critics remain unconvinced [22, 29, 37, 53]. A major problem with many studies has been a failure to control for "selection bias" and home background. That is, the superior achievements of alumnae from women's colleges may reflect only that prestigious women's colleges enroll women of superior academic ability who may have attended superior high schools. …