The First International and Interdisciplinary Conference on Modelling and Using Context, held in Rio de Janeiro, in January 1997, gave rise to the present book, which contains a selection of the papers presented there, thoroughly refereed and revised. The treatment of contexts as bona fide objects of logical formalization has gained wide acceptance, following the seminal impetus given by McCarthy in his Turing Award address. The field of natural language offers a particularly rich variety of examples and challenges to researchers concerned with the formal modelling of context, and several chapters in the volume deal with contextualization in the setting of natural language. Others adopt a purely formal-logical viewpoint, seeking to develop general models of even wider applicability. The 12 chapters are organized in three groups: formalization of contextual information in natural language understanding and generation; the application of context in mechanized reasoning domains; and novel non-classical logics for contextual application.