Blonde narrator Laura invites dark friend Marissa over after school; the two six-year-olds play one active, imaginative game after another--ballet, secret language, escaping from robots, hospital, pirates--till it's time for Marissa to go home. Rosner's gracefully curvilinear draughtsmanship and delicate watercoloring raise this above the ordinary, her figures and designs dancing With exuberant life. The two mothers occasionally join in the fun; the illustrations imply that they are also warm friends who delight in one another's company. For the sake of reality, Laura and Marissa have one brief spat, but the real point of this romp is a celebration of creative play. The illustrations' casual depiction of multiracial characters is a nice touch. A good picture book to share with preschoolers, or for beginning readers to enjoy on their own.