Dutch civil law allows courts of first and second instance to refer preliminary questions to the Supreme Court. In mass claim disputes there may be a concurrence between the safeguards of the preliminary ruling procedure and the protection provided by Directive 2020/1828 on representative actions for the protection of the collective interests of consumers. This working paper addresses several issues regarding this concurrence. These include legal certainty, the influence of non-parties, the costs and the duration. The authors come to the conclusion that the preliminary ruling procedure can be very useful in mass claim disputes, albeit that both the lower courts and the Supreme Court need to align their practice more closely with the safeguards of the Directive on a number of points. These findings may be relevant for other European jurisdictions that recently introduced a preliminary ruling procedure, or that are about to insert a preliminary ruling procedure in their civil procedural law system.