These are the proceedings of the 2nd International Workshop on Programming Multi-agentSystems(ProMAS2004),heldinJuly2004inNewYork(USA)asan associated event of AAMAS 2004, the main international conference dedicated to autonomous agents and multi-agent systems. The idea of organizing such an event was discussed during the Dagstuhl s- inarProgramming Multi-agent Systems Based on Logic (see [2]), where the focus was on logic-based approaches. It was felt that the scope should be broadened beyond logic-based approaches, and thus ProMAS came into being (see [1] for the proceedings of the ?rst event, ProMAS 2003). Meanwhile, a Steering Committee (Rafael Bordini, Mehdi Dastani, Jurgen .. Dix, Amal El Fallah Seghrouchni) as well as an AgentLink III Technical Forum GrouponProgrammingMulti-agentSystems wereestablished(thelatteronewas founded on 30 June/1 July 2004 in Rome, Italy (see http:// www.cs.uu.nl/ mehdi/al3tf8.html). Moreover, a Kluwer book on the same topic is underway (to appear early in 2005) and the third workshop ProMAS 2005 will be organized within AAMAS 2005 (see http://www.cs.uu.nl/ProMAS/ for up-to-date information about ProMAS).