As the play makes clear, Rosalind's cross-dressing as Ganymede is the means by which she and Orlando come to fully realize their love for one another. Cross-dressing was not uncommon in Shakespeare's plays, and it played a central part in the plots of Twelfth Night and The Merchant of Venice. Notably, cross-dressing was usually a comic convention that did not typically appear in tragedies, as it usually leads to dramatic irony, misunderstanding, and general antics reserved for comic performance.
Generally speaking, early modern English children were dressed similarly in their early years, regardless of gender. Boys and girls alike would wear dresses and gowns until a specified time when the boys would be "breeched," or put into pants. Often, there was a breeching ceremony, making the shift a formal affair that marked boys' first transition out of childhood. While breeching did not necessarily happen at the same time for all English boys, it generally occurred between the ages of five and eight years old. This practice lasted well into the nineteenth century, with many arguing that it was still common in the early 1900s.
Thus, Rosalind's choice to disguise herself as Ganymede (rather than another woman, as Celia does), is a calculated one, likely based on the importance of homosocial intimacy in early modern England. This element of the play is complicated, however, by the fact that female roles on the early modern English stage were played by boys or young men. Thus, the Rosalind who appeared in original productions of the play would have likely been an adolescent boy, playing a woman, dressed as a man. This certainly would have added another layer of entertainment for the audience, but it also becomes a meta-theatrical commentary on the nature of the early modern stage and its relationship to society: while cross-dressing on the streets of London was considered taboo, the same phenomenon was widely accepted as common theatrical practice in the playhouses.
