This paper presents the preliminary findings of a study on US influence on the EU’s chemicals regime. The initial results of interviews conducted among major stakeholders (the European Commission, the Chemicals Agency ECHA, US Environmental Protection Agency EPA, and Brussels-based US lobbying organisations) indicate that US lobbying did not stop in 2006 when the Chemicals Regulation REACH was passed. Lobbying has, in fact, continued during the rule implementation stage. To this end, this paper raises and attempts to answer two questions. Firstly, what are the different means or avenues available to the US in shaping rule implementation? Secondly, how is the content of chemicals legislation shaped in implementation to take into account US interests? Demonstrating how transatlantic chemicals cooperation has evolved from a passionate romance into a mature relationship, the paper also provides a more general description of non-EU influence on the development of EU law and policy.