The Efficacy of Single-Sex Education: Testing for Selection and Peer Quality Effects

To address selection and peer quality effects in tests of the efficacy of single-sex schools, the achievement of girls attending a public single-sex middle school in the Southwest United States ( N = 121) was compared to that of (a) girls who applied but were not admitted to the same school ( N = 229) and (b) girls who applied to and attended a coeducational magnet school ( N = 134). Achievement scores were collected over 3 years for the ethnically diverse participants (41 African Americans, 27 Asian Americans, 163 European Americans, 251 Latinos, and two Native Americans). After controlling for selection and peer quality effects, there was no significant effect of the gender composition of schools on achievement. Implications for educational policy are discussed.