The right to claim contribution in competition law is ensured by EU law but its exercise takes place under national laws. This Chapter investigates English, German, French and Polish rules on contribution and their application in the competition law context. On the one hand, the assessment is pragmatic. It analyses questions that are likely to appear when pursuing contribution claims. Does a right to claim contribution exist in a given legal order? On what basis and in which form can contribution be claimed? Against whom can contribution be claimed? What legal test must be met to receive contribution? What is the criterion for allocating liability between antitrust infringers? The analysis shows that the allocation of liability can be debated, as there are several possible methods of dividing liability: relative fault, causation, illicit gains, values of sales, market shares and pro capita. At the same time, the Chapter reflects on whether the requirements and modifications stemming from EU competition law require the adoption of a competition law-specific approach to contribution and makes proposals on how rules on contribution can be improved.