Quote from the summary of a paper recently published in the prestigious journal Science:
"There is no well-designed research showing that single-sex (SS) education improves students' academic performance, but there is evidence that sex segregation increases gender stereotyping and legitimizes institutional sexism."
The Pseudoscience of Single-Sex Schooling.
Diane F. Halpern, Lise Eliot, Rebecca S. Bigler, Richard A. Fabes, Laura D. Hanish, Janet Hyde, Lynn S. Liben, and Carol Lynn Martin
Science. 23 September 2011: 333 (6050), 1706-1707. [DOI:10.1126/science.1205031]
Quotes from the related press release:
".... there is little concrete evidence to support claims that single-sex schools are a better learning environment."
"Some supporters of single-sex schools claim that brain differences between boys and girls require different teaching styles. But neuroscientists have found few differences between male and female brains, and none has been linked to different learning styles."
Indivero, Victoria M. (2011) Sex segregation in schools detrimental to equality. (press release) EurekAlert. September 22nd 2011.