This chapter assesses the antitrust fines and private penalties imposed on the participants of 260 international cartels discovered during 1990–2003, using four indicators of enforcement effectiveness: investigatory speed and confidentiality and two indexes of the harshness of monetary sanctions. First, the United States is almost always the first to investigate and sanction international cartels, and its investigations are about seven times faster than EU probes. Second, U.S. investigations were more likely to be kept confidential than those in Europe, but the gap nearly disappeared since 2000. Third, median government antitrust fines average less than 10% of affected commerce, but the median ratio rises to about 35% in the case of multi-continental conspiracies. Civil settlements in jurisdictions where they are permitted are typically 6 to 12%. Fourth, fines on cartels that operated in Europe averaged a bit more than half of their estimated overcharges; those prosecuted only in North America paid civil and criminal sanctions of roughly single damages; and global cartels prosecuted in both jurisdictions typically paid less than single damages.