All we need to do to take part in the Rāsa Dance Festival is fight off our family relatives who stop us and visit Krishnā in the forest when He summons you by playing His flute. But you get to do it as a female partner of Krishnā.
And all we need to do to take part in the Nagar Sankīrtan Festival is associate with people interested in the Hare Krishnā Mahā Mantrā and sing as a group. It doesn’t matter if you’re a male or female.
On a more transparent side, you can participate in the Rāsa Dance even being a male. How? By perfecting the mystic power of merging into Krishnā’s body, creating a seemingly “I and Krishnā are one” appearance and also by perfecting the mystic power of expanding out of Krishnā’s body and then dancing with Mother Rādhārānī, creating a seemingly “It is Krihsnā Himself only Who is dancing with Rādhā” appearance. Well this is a deception, but Krishnā can fulfill any desire, you only need to submit your desire as a prayer to Him.
And in the Nagar Sankīrtan you don’t sing in groups of mixed sex, i.e. males sing in groups of males and females sing in groups of females. Why? When you do Nagar Sankītan, you are actually being summoned by Gaurāngā, and Gaurāngā, heck, doesn’t like female company. So we ask the females to stay in a seperate group, which is in a good distance away from the male group. Why such partiality to the females? Well who asked you to worship Gaurāngā mother? Go worship Krishnā. Besides, the males do have the same discomfort of partiality in Krishnā’s Rāsa Dance. But you can nevertheless perfect the mystic power of changing form from female to male and thus sing together with Gaurānga. Gaurānga will accept if you submit such prayers of desiring mystic power and thereafter sing together with Him.
Nanda Mahārājā's Palace 