Missouri has no single-sex charter schools yet, although a few charters do offer single-sex classrooms. So we haven’t run into the legal dilemma single-sex charters in Illinois may face. The Illinois charter school law prohibits charters from discriminating in admissions based on gender, as does Missouri’s law. This article (link via Edspresso) mentions a possible situation that administrators in Illinois are anticipating:

The School Board’s administration said Tuesday the school can’t, by law, discriminate against female applicants, and if a girl applies and is chosen by computerized lottery, she’d be a student there, too.

It seems that the charter schools don’t expect students of the opposite sex to apply. The two single-sex high schools in Chicago have been open for several years without problems. I doubt any teenage boy would want to attend the Young Women’s Leadership Charter School of his own initiative, but it could be that adults will decide to challenge the schools’ legality.