Seniority systems – schemes that allot improving employment rights or benefits to employees as their length of employment increases – have not been widely studied. This report provides the first comprehensive study comparing the design and spread of seniority-based entitlements (SBEs) in Europe and mapping related policy debates. It is primarily based on contributions from the Network of Eurofound Correspondents, covering the 28 EU Member States and Norway, but also presents aggregate seniority-earnings curves for the EU based on data from the Structure of Earnings Survey. The aim of the report is to take stock of the currently existing different types of SBEs in the private and public sectors. It concludes that despite an obvious trend to remove them from regulations or reform them, a substantial amount of such entitlements is here to stay. Paradoxically, countries which have regulations on seniority pay in place tend to have flatter aggregate seniority-earnings curves than countries without such regulations.