Progress towards UAP is very difficult without the involvement of national libraries. A national acquisition plan can be supported in various ways by a national library; if it plays a central role, this could take the form of a dedicated document supply centre or an integrated reference/supply collection. Document supply, whether centralized or involving union lists, needs planning, coordination and management, for which the national library is a natural centre. Retention for future availability also requires national planning and possibly a national repository. To play a proper role in UAP national libraries may need to reconsider their nature and functions.