No professional actresses appeared on the English stage before 1660. All the female roles in Shakespeare's plays were originally played by male actors. This is no doubt one explanation of the popularity of plots in which girls dress up as boys.
Boy actors underwent a rigorous training as apprentices to senior members of the acting companies, and there is no reason to suppose that they lacked expertise. In Shakespeare's time there were also companies composed exclusively of boys, which at times constituted serious rivals to the adult companies. A passage in Hamlet (II. ii.339–61) alludes to their success.
Subjects: Shakespeare Studies and Criticism.