A recent comparative analysis of the content of lobby regulation schemes published in this journal casts measures developed at European Union (EU) level as the vanguard of a ‘new wave’ of strong lobby regulation across Europe. Other assessments characterise EU lobby regulation as weak, primarily based on the voluntary nature of a succession of registers of lobbyists, as well as the quality of data within them. We examine these competing perspectives through a focus upon the EU Transparency Register (TR), now exceeding 5500 individual entries. We set the scheme within a ‘transparency for legitimacy’ pathway and note its differentiation from predecessor instruments by its breadth of scope. We assess the extent of coverage of its core targets through a comparison of the entries in two of its categories (business related and NGOs) with other information sources; we estimate its coverage of the intended population to be approximately three-quarters of business-related organisations and around 60 per cent of NGOs. These are sizeable proportions for a voluntary (albeit incentivised) register, but not sufficient yet to justify the ‘de-facto mandatory’ claim for it made at its launch in 2011. We then assess the structure of the Register, the incentives to join it and its population in detail. The quality of the data in the TR has progressively improved from the starting point of its predecessor schemes. Nonetheless, there are one-third of all entries in the Register that did not choose ‘European’ as one of the interests they represent, but instead another territorial level. Although some data quality problems remain, with a fringe of questionable entries, the reliance upon those in the Register to monitor it has driven up standards of data entry among the main lobbying players. Nonetheless, there are faults of design and nomenclature. A key juncture during the registration process involves a choice of category to appear in the Register, affecting the disclosure and presentation of public information. We identify 15 per cent of entries in the NGO category, which could better be re-assigned to other categories. We identify the boundary points from which the data can be put to research use, involving the identification of a ‘European interest’ represented and use of a Brussels address, which makes the data less prone to outliers. Nonetheless even after this operation there remain problems in aggregating data on some indicators (particularly head counts of lobbyists) because of the extent of the extreme cases. However, some clear pictures emerge from the data; after removing duplicated entries from the Register, and discounting a small number of inappropriate outliers, we present the first such results from it. A key finding is that the differences in reported resources are less than might be expected between business-related organisations and NGOs. One area where there is substantial difference concerns the receipt of European Union (EU) funding for civil society organisations. The EU political system has long had substantial funding regimes in place for NGOs. We are able to provide the most accurate information yet available about the extent of NGO reliance upon EU political institutions. NGOs with a Brussels base representing a European interest and that receive a grant from EU institutions draw an average of 43 per cent of their budget from such sources. Finally, we place the TR within traditions of comparative lobby regulation. This analysis comes ahead of a scheduled review of the scheme by the European Commission and European Parliament during 2013, and at a time when most EU member states have established regulatory instruments or currently have them under active consideration.