Intelligent agents will be the necessity of the coming century. Software agents will pilot us through the vast sea of information, by communicating with other agents. A group of cooperating agents may accomplish a task which cannot be done by any subset of them. This volume consists of selected papers from PRIMA’99, the second Paci c Rim InternationalWorkshop on Multi-Agents, held in Kyoto,Japan, on Dec- ber 2-3, 1999. PRIMA constitutes a series of workshops on autonomous agents and mul- agent systems, integrating the activities in Asia and the Pacic rim countries, such as MACC (Multiagent Systems and Cooperative Computation) in Japan, and the Australian Workshop on Distributed Arti cial Intelligence. The r st workshop, PRIMA’98, was held in conjunction with PRICAI’98, in Singapore. The aim of this workshop is to encourage activities in this e ld, and to bring togetherresearchersfromAsiaandPacic rimworkingonagentsandmultiagent issues. Unlike usual conferences, this workshop mainly discusses and explores scienti c and practical problems as raised by the participants. Participation is thus limited to professionals who have made a signi cant contribution to the topics of the workshop. Topics of interest include, but are not limited to: - multi-agent systems and their applications - agent architecture and its applications - languages for describing (multi-)agent systems - standard (multi-)agent problems - challenging research issues in (multi-)agent systems - communication and dialogues - multi-agent learning - other issues on (multi-)agent systems We received 43 submissions to this workshop from more than 10 countries.