Intelligent agents are one of the most important developments in computer science of the past decade. Agents are of interest in many important application areas, ranging from human-computer interaction to industrial process control. The ATAL workshop series aims to bring together researchers interested in the core/micro aspects of agent technology. Specifically, ATAL addresses issues such as theories of agency, software architectures for intelligent agents, methodologies and programming languages for r- lizing agents, and software tools for applying and evaluating agent systems. One of the strengths of the ATAL workshop series is its emphasis on the synergies between theories, languages, architectures, infrastructures, methodologies, and formal methods. This year s workshop continued the ATAL trend of attracting a large number of high quality submissions. In more detail, 71 papers were submitted to the ATAL 2000 workshop, from 21 countries. After stringent reviewing, 22 papers were accepted for publication and appear in these proceedings. As with previous workshops in the series, we chose to emphasize what we perceive asimportantnewthemesinagentresearch. Thisyear sthemeswerebothassociatedwith the fact that the technology of intelligent agents and multi-agent systems is beginning to migrate from research labs to software engineering centers. As agents are deployed in applications such as electronic commerce, and start to take over responsibilities for their human users, techniques for controlling their autonomy become crucial. As well, the availability of tools that facilitate the design and implementation of agent systems becomes an important factor in how rapidly the technology will achieve widespread use.