The purpose of this study is to investigate the metatheatricality of Harris' plays marked by the device of 'play-within-a-play' - Androcles and the Lion, Arkansaw Bear, and Punch and Judy. In his metatheatrical plays Harris shows that characters perform for themselves and others. The framework that inner performance is going on within the outer frame play is formed on the stage, and this device reminds the audience in the seats that they are representing reality but that they are only in the middle of performing on the stage. Based on this point of view, this study explores fictionality of character, and play. In Androcles and the Lion, the most-performed children's play in America, the metatheatrical elements are shown in the style of commedia dell'arte, which attacks the rigidity of characters' identity in the Roman society. Another well-known children's play, Arkansaw Bear consists of realistic frame play and fantastic inner play in the mind of a girl, both of which function as a mirror each other and help to sustain aesthetic distance to death and reality on the stage. In Punch and Judy, the structure of frame play and inner puppet play reminds that what's going on in the play is just a fictional play and reflects history of children's puppet show. Harris' unique metatheatricality, the heightened awareness of his own artistic medium, offers children educational opportunity to learn about how a play is performed on the stage and contributes to convey mature theme through children's imaginary participation in the process of playmaking on the stage.