Contributors to start by asking how we evaluate DLs - how we can understand them in order to build better DLs - but they move beyond basic concerns to explore how DLs make a difference in people's lives and their social world, and what studying DLs might tell us about the information , knowledge, and social and cognitive processes. Topics considered include documents and society; real boundaries of a "library without walls", the ecology of the digital library, usability and evaluation, information and institutional change; transparency as a product of the convergence of social practices and artifacts of the information, and collaborative knowledge construction in digital libraries.