The paper assesses the effectiveness of the European Union’s Emission Trading System, which was launched in 2005 to reduce greenhouse gas (GHG) emissions across the bloc. Initially, the system covered around 11,000 energy-intensive industrial installations. The authors examine the EU’s “cap-and-trade scheme” in terms of the Pigovian taxation and Coase bargaining models, two classic instruments for the internalization of externalities. The approach differs depending on which method is used for the initial allocation of emission allowances. Currently, the predominant method in the EU is the so-called costless grandfathering, which is equivalent to the model proposed by Coase, according to the authors. In the course of the analysis, Pytka and Kuszewski assess the effectiveness of the cap-and-trade scheme by employing two alternative approaches, an econometric analysis based on a test of linear restrictions and a model using a “differences-in-differences” estimator. For the linear-restriction models, data for EU countries from 2003 and 2005 were used, whereas the differences-in-differences analysis was carried out using data for EU countries and a control group of non-EU countries for the 2003-2007 period. The analysis shows that the system is ineffective in its current form, the authors conclude.