The Canadian Centre for Architecture (CCA) in Montreal, devoted to the history and theory of the art of architecture, was founded in 1979 and opened to the public in 1989. It is defined in its mission statement as a museum and study centre, and its Library was conceived and developed by its Founding Director, Phyllis Lambert, to serve both halves of this mission. This article describes some of the ways in which its dual function permeates the Library’s operations and activities. It is our belief that the CCA Library adds value to its collections and services precisely by bridging the old, old gap between the traditional museum library and the traditional research library.