The integration of girls and boys in youth sports leagues are encouraged for children ages 8-years-old and younger. However, coed sports are not appropriate for children above age 8 if the minority gender (a girl playing in a boys league or boy playing in a girls league) plays at an advanced skill level and/or is a greater physical size.
Determining whether coed youth sports are appropriate in cases where the children are 9-years-old and older must be decided on an individual basis, depending on the circumstances involved in that particular situation with the final determination being the parent of the child in question.
In some cases, it may be appropriate for an 11-year-old girl to participate in a youth league if she is the appropriate physical size and skill level. However, in most cases it would not be appropriate for an 11-year-old boy to participate in a league intended for girls of that age.