Rarely when single-sex Catholic secondary schools convert to coed school organization is the potential loss of gender-specific benefits addressed. Since the movement to coeducation is seldom accompanied by the return of a "converted" school to single-sex status, the incalculable loss to the traditional gender diversity of school organization is alarming, especially when research findings show strong and sustaining effects for these schools, most notably for women and minorities. While boys' schools resemble the factory model of schooling (structured, functional, economically efficient, and focused on a delivery system of education), girls' schools resemble an ecological model of schooling: one that fosters inclusiveness, interaction, caring, values, and attention to the context of education not as a delivery system, but as a way of life. Catholic education has distinct approaches toward the education of girls and boys; when these approaches are "blended" in a coed school, the distinctiveness is lost. Moreover, achievement advantages found in Catholic schools can be attributed to single-sex Catholic schools, not to Catholic schools generally. Students in single-sex schools display more positive academic interests, attitudes, and behaviors than students in coed schools. (13 references) (KM)