Abstract. In this paper, we describe the declarative agent programming language Jadl (JIAC Agent Description Language). Based on threevalued logic, it incorporates ontologies, FIPA-based speech acts, a (procedural) scripting part for (complex) actions, and allows to define protocols and service based communication. Rather than relying on a library of plans, the framework implementing Jadl allows agents to plan from first principles. We also describe the framework and some applications that have been implemented.