In early 2011 the authors of this presentation completed a guidance document for MSFD Descriptor 5, Eutrophication. In mid-2011, the science supporting that document was published in the journal Estuarine, Coastal, and Shelf Science. In this talk we review the main findings of the guidance document, focussing on the potential assessment methods, spatial and temporal issues, monitoring guidelines and challenges, and the ways in which the recommendations of the guidance task group were translated into the subsequent Commission Decision. We then review actions that have been pursued since the guidance was published. These include: Type 1 actions - scientific and/or application developments relevant to the Eutrophication Descriptor and its assessment; and Type 2 actions - ways in which EU Member States are interpreting and applying the guidance produced. Examples provided for Type 1 include (i) reprocessing the Oxygen Risk Index for Europe, including the most recent satellite data, by the EU’s Joint Research Centre; (ii) analysis of a Northern European data set from the HARMONY project on the consequences of the Commission Decision to leave out the ‘Benthic Invertebrates’ indicator from the secondary (indirect) effects of eutrophication; and (iii) recent results from the OSPAR modelling group about the assessment of transboundary responsibilities in eutrophication of the OSPAR area. For actions of Type 2, we provide an overview of the practical mplementation of MSFD Descriptor 5 in EU Member States, with respect to approach and progress, and focus in greater detail on recent proposals for application in the UK, in the context of the guidance provided.