This is a quantitative analysis of the European Commission’s cartel decisions in the 2010–2019 decade. It assesses the way the Commission’s 2006 guidelines on fines were applied in practice and the operation of the leniency and settlement procedures. It also provides an overview of the types of cartels prosecuted, how they were detected, and how long the Commission took to investigate a cartel. It looks at rends in the Commission’s enforcement activity and assesses some frequently made claims such as whether recidivism is rife; whether the Commission’s leniency program is excessively generous and disproportionately benefits larger, more culpable firms; how much the settlements procedure reduces the length of the Commission’s investigations; and why the Commission takes so long to conclude its investigations.