As the European Union greenhouse gas emission trading scheme (ETS) is emerging, it seems interesting to look back on previous experiments and to bring together a few elements of reflection about the pertinence of ETS as a new policy tool to regulate industrial pollution. So far, several regulatory tools have been used to decrease pollution. This article focuses on two of them, command-and-control (CAC) and ETS. There is no simple answer to which one is more efficient. It depends strongly on the context. Given a few elements outlined in this paper, the choice of an ETS to abate industrial emissions of greenhouse gases in the European Union (EU) can be considered pertinent. But, ultimately, what makes a scheme environmentally efficient is not the tool in itself (ETS or CAC) but the ambition of the target. Hence the design of the National Allocation Plans setting the emission caps are of paramount importance. They will make the EU ETS either a useless mess or an effective climate change mitigation policy tool. (c) 2004 Elsevier Ltd. All rights reserved.