<em>Girl Before a Mirror</em> shows Picasso's young mistress Marie-Thérèse Walter, one of his favorite subjects in the early 1930s. Her white-haloed profile, rendered in a smooth lavender pink, appears serene. But it merges with a more roughly painted, frontal view of her face—a crescent, like the moon, yet intensely yellow, like the sun, and "made up" with a gilding of rouge, lipstick, and green eye-shadow. Perhaps the painting suggests both Walter's day-self and her night-self, both her tranquillity and her vitality, but also the transition from an innocent girl to a worldly woman aware of her own sexuality.