This paper introduces a general methodology for the development and
study of conversational systems.  Closer coupling of linguistic and
psycholinguistic theories about dialogue with the development of
dialogue systems allows each to inform the other more fully.  Three
activities support our goals.  We develop theories through the
empirical investigation of dialogue in conversational settings.  We
use this to inform our theoretical research on dialogue and our design
of advanced conversational interface systems.  We then experiment with
these systems to compare their behavior to human-to-human
interactions.  This paper discusses a study and analysis of
conversations about library information, the development of a system
based on this analysis, lessons learned, and future goals.