The document attached is the result of several years of experience of work on the issue of nanomaterials carried out by BUND, CIEL and ClientEarth. It draws on participation in consultations, expert groups and from interaction with all stakeholders (including Member States, European Commission, and European Parliament, the NGO community, trade unions and industry associations). It presents an initial concept note in the form of an Explanatory Note typical of a Commission proposal, to present the basic idea of a horizontal piece of legislation covering nanomaterials. This concept note suggests that the best way to address the shortcomings in the regulation of nanomaterials is to have a separate horizontal instrument that foresees general principles which apply to all nanomaterials on the market in all relevant fields (chemicals, products and environmental protection legislation). In addition to setting general principles, the proposed instrument would amend REACH as the cornerstone for filling the regulatory gaps on nanomaterials and nanotechnologies as well as sectoral chemicals legislation.