This article considers several economics-related issues in the theory of damages -- especially in private antitrust cases, drawing possible lessons for Europe from US experience. It begins with an overview of different rationales for such damages and their implications. Such rationales include: making the plaintiff whole; preventing unjust enrichment; and incentives to private plaintiffs. Problems from US experience include whether to allow recovery by indirect purchasers (Illinois Brick), and the creation by treble damages of incentives to bring meritless cases that can then be settled for profit