Many of the coteries here are assembled by family association and parental club membership. Sometimes the young woman herself is the member but it's not often. Quite a few of these organizations are more than 100-years-old.
You can also check out the National League of Junior Cotillions. They now have a Presentation Society.
http://www.nljc.com/debutantecotillion.htm
My deb year was tons of fun and I look forward to when Little Miss aopirose makes her bows.