\input zb-basic \input zb-ioport \iteman{io-port 05731090} \itemau{Kersey, Cynthia; Di Eugenio, Barbara; Jordan, Pamela; Katz, Sandra} \itemti{KSC-PaL: A peer learning agent.} \itemso{Aleven, Vincent (ed.) et al., Intelligent tutoring systems. 10th international conference, ITS 2010, Pittsburgh, PA, USA, June 14--18, 2010. Proceedings, Part II. Berlin: Springer (ISBN 978-3-642-13436-4/pbk). Lecture Notes in Computer Science 6095, 72-81 (2010).} \itemab Summary: We have developed an artificial agent based on a computational model of peer learning we developed. That model shows that shifts in initiative are conducive to learning. The peer learning agent can collaborate with a human student via dialog and actions within a graphical workspace. This paper describes the architecture and implementation of the agent and the user study we conducted to evaluate the agent. Results show that the agent is able to encourage shifts in initiative in order to promote learning and that students learn using the agent. \itemrv{~} \itemcc{} \itemut{Peer Agent; Knowledge Co-construction; Initiative} \itemli{doi:10.1007/978-3-642-13437-1\_8} \end