Team ISIS ISI Synthetic successfully participated in the rst 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 of RoboCup'97 the most popular among the three RoboCup'97 leagues. In terms of research accomplishments, ISIS illustrated the usefulness of an explicit model of teamwork both in terms of reduced development time and improved teamwork exibility. ISIS also took some initial steps towards learning of individual player skills. This paper discusses the design of ISIS in detail, with particular emphasis on its novel approach to teamwork.