The paper starts with a brief historical overview of measurement and assessment activities that characterized Italian libraries in the last thirty years, to understand if these are still effectively sustainable. In particular, the paper focuses on terms “assessment” and “sustainability”, analyzing their relationships (and linguistic implications) in terms of “assessment of sustainability” and “sustainability of assessment”. An important question closes the reflection: can sustainability become a new paradigm and a strategic opportunity for Italian libraries and librarianship, also in terms of assessment, in today’s information society?