The Robotics Institute at Carnegie Mellon University is very active in the development of robots whose function relies on efficient communication and interaction with people. Published in 2003, this comprehensive study looks at the history, operation, and classification of a large sampling of socially interactive robots from both industry and academia. The authors define and discuss several concepts related to human-robot interaction, such as emotion, embodiment, and personality. They also address a number of design and evaluation issues that are important for assessing a robot's social characteristics. The paper concludes with a look ahead at future research and applications for these types of robots.