Abstract. Extensible Dependency Grammar (XDG) is a graph description language whose formulas can be solved by constraint programming. XDG is designed so as to yield a declarative approach to natural language processing, in particular to parsing and generation. In this paper, we present the XDG Development Kit (XDK), the first XDG-based grammar development system, which we have implemented in Mozart/Oz, thereby making full use of its multi-paradigmatic nature. The XDK supports an expressive lexicon specification language which which has not been published previously.