We use a panel dataset of about 5,000 Lithuanian firms between 2003 and 2010, to assess the impact of the EU ETS on the environmental and economic performance of participating firms. Using a matching methodology, we are able to estimate the causal impact of EU ETS participation on C02 emissions, C02 intensity, investment behaviour and profitability of participating firms. Our results show that ETS participation did not lead to a reduction in C02 emissions, while we identify a slight improvement in C02 intensity. ETS participants are shown to have retired part of their less efficient capital stock, and to have made modest additional investments from 2010. We also show that the EU ETS did not represent a drag on the profitability of participating firms.