\input zb-basic \input zb-ioport \iteman{io-port 01771048} \itemau{Tambe, Milind; Adibi, Jafar; Al-Onaizan, Yaser; Erdem, Ali; Kaminka, Gal A.; Marsella, Stacy C.; Muslea, Ion} \itemti{Building agent teams using an explicit teamwork model and learning.} \itemso{Artif. Intell. 110, No. 2, 215-239 (1999).} \itemab Summary: Multi-agent collaboration or teamwork and learning are two critical research challenges in a large number of multi-agent applications. These research challenges are highlighted in RoboCup, an international project focused on robotic and synthetic soccer as a common testbed for research in multi-agent systems. This article describes our approach to address these challenges, based on a team of soccer-playing agents built for the simulation league of RoboCup -- the most popular of the RoboCup leagues so far. To address the challenge of teamwork, we investigate a novel approach based on the (re)use of a domain-independent, explicit model of teamwork, an explicitly represented hierarchy of team plans and goals, and a team organization hierarchy based on roles and role-relationships. This general approach to teamwork, shown to be applicable in other domains beyond RoboCup, both reduces development time and improves teamwork flexibility. We also demonstrate the application of off-line and on-line learning to improve and specialize agents' individual skills in RoboCup. These capabilities enabled our soccer-playing team, ISIS, to successfully participate in the first international RoboCup soccer tournament (RoboCup'97) held in Nagoya, Japan, in August 1997. ISIS won the third-place prize in over 30 teams that participated in the simulation league. \itemrv{~} \itemcc{} \itemut{soccer-playing team} \itemli{doi:10.1016/S0004-3702(99)00022-3} \end