ActiMates™ Barney™ represents a new form of interactive learning product for two- to five-year old children: a small computer that looks like an animated plush doll. He can be used as a freestanding toy and, by means of a wireless radio link, he can interact with PC-based software and linear videotapes. In each mode, Barney takes advantage of children’s social expectations about playmate performance to engage the user in learning interactions. The theory and practice behind Barney’s performance in each mode (freestanding, with the computer, and with the television) are described, as well as how key research results shaped the interface across the different modes.