Linguistic theories play an important role in natural language processing applications. This volume contains several detailed studies of questions concerned with the implementation of contemporary grammatical theories (LFG, GPSG, CUG, GB) as well as their application to the formal description of natural languages. The linguistically-oriented studies concentrate on word order, non-local dependencies and coordination, and on the relation between syntax and semantics. A second set of contributions investigates how desirable properties of linguistic formalisms (such as restrictiveness, decIarativeness, rigor, and linguistic felicity) can be maintained without sacrificing computational efficiency or leading to excessive computational complexity. These papers show clearly that theoretical and computational linguistics can make significant contributions to each other. The studies that focus on implementational issues discuss the aspects of linguistic theories that should be incorporated in natural language processing systems and describe attempts to provide efficient and flexible implementations of systems based on these theories.