This chapter discusses ETS effects on EU steel companies. A first main finding is that the steel sector shows a kind of ‘Janus face’ in the field of climate change politics. In the high-profile ETS context, the sector has held a reluctant and sceptical stance from the very start, evident also in recent process of establishing industrial benchmarks. These developments may easily overshadow the other more technical and low-profile face, where a long-standing technology development process has given birth to the promising ULCOS programme. Second, although steel companies may well have been ‘carbon fat cats’ for a period, interesting changes have taken place, in the form of more short-term energy efficiency initiatives and more long-term technology development initiatives. This is underpinned by information about aggregate climate strategies and a more in-depth study of the major company ThyssenKrupp and the smaller SSAB (i.e. Swedish Steel AB). Third, as regards the specific impact of the ETS on companies in this sector, the impact on corporate leaders thinking and awareness stands out as the most important effect so far. As one steel company interviewee expressed it, there has been a considerable ‘mind change’ brought about by the ETS, not least induced by the changes adopted in 2009. Still, substantial uncertainty attends the functioning also of a revised ETS unless it can be matched by corresponding global measures.