Avatars in online games and worlds are seen as players ’ key representations in interactions with others. It is surprising then that this aspect of game play has not received much attention in research, in particular what concerns playergenerated avatars. In this paper, we investigate the avatar design and identity play within a large-scale tween virtual world called Whyville.net with more than 1.5 million registered players ages 8-16. One unique feature of Whyville is the player’s ability to customize one’s avatar with various face parts and accessories, all designed and sold by other players in Whyville. Our findings report on the expressive resources available for avatar construction, individual tween players ’ choices and rationales in creating their avatars, and online postings about avatar design in the community at large. With the growing interest in playergenerated content for online worlds such as Second Life, our discussion will address the role of avatars in identity play and self-representation as well as the social issues that arise within the game world.