The mood of As You Like It is dreamy and whimsical. The setting of the mystical Forest of Arden, as well as the play's pastoral elements and use of irony, support this mood.
There was a real-life “Forest of Arden” in England, not far from Stratford-Upon-Avon, where Shakespeare was born. However, it would seem that the play is not set here; the setting is explicitly French from the first scene. While there is a similar forest in France, the play's setting is never referred to by its French name (the “Ardenne Forest”). The Forest of Arden, like the people within it, is neither here nor there—it is an undefined place of transition and escape. The presence of lions, pythons, and Roman gods establishes Arden as a place where normal rules of nature do not apply, and where imagination can bleed into reality.
The Forest of Arden is also a space in which the normal rules of culture do not apply, a standard trope of the pastoral genre. Rosalind, Celia, Orlando, and Oliver assume new identities or leave behind old ones. Royalty live side by side with shepherds, as social hierarchy collapses in an ideal natural setting. The effect is strange and dream-like: the characters have entered into a landscape where literally anything can happen. What’s more, most of the action in As You Like It happens in the very beginning (the attempt on Orlando’s life, the exile of Orlando and Rosalind) and at the very end (the marriage scene). Most of what happens in the middle is conversation: about love, about marriage, about life. Most of the play is these characters wandering, wondering about what their lives could be like—dreaming, if you like, out loud.
Shakespeare’s use of dramatic irony keeps the play from becoming too slow. Dramatic irony injects the storyline with whimsy, humor, and intrigue. The audience learns early on that Rosalind is masquerading as Ganymede, and Celia as a shepherdess, so all of their subsequent scenes are touched by this knowledge. Whether it is Ganymede mourning that he was not born a woman, or Oliver hastily promising to become a shepherd to marry Celia, the irony of their situation offers up countless opportunities for unexpected comedy and pathos.