Headlines are made when the European Commission prohibits a merger, but this is actually very rare. Clearances subject to conditions (i.e. remedies) happen ten times as frequently, but have received far less attention in academic literature. This book provides an empirical assessment of the effectiveness of merger remedies, employing a novel simulation methodology based on formal economic theory. The authors were given unprecedented access to data available to case handlers, concerning a range of remedied mergers covering 21 markets. Using this they have adapted simple simulation techniques to appraise the competitive effects of these mergers and the impact of potential and actual remedies. Ex-ante results are then compared with ex-post impact to examine the actual effectiveness of remedies. The results provide a critique of both simple market share analysis and remedy design. This research thus contributes to economics research and practical merger policy.