It is tempting to view the United States as a model for the harmonization of rules of civil procedure. This chapter argues that there may be lessons to learn from the US experience, but that there are reasons to be skeptical about the usefulness of the US model for efforts to harmonize the procedural rules of EU members. The rules of civil procedure are not as harmonized in the United States as commonly assumed. Judicial cooperation in the United States is in any event based less on extensive harmonization than on a system of interjurisdictional deference made possible by the twin foundations of full faith and credit and minimum procedural standards—foundations that do not yet appear to be sufficiently well developed in the EU to make this model immediately workable there. Finally, for reasons of legal and political culture, the process of making rules of civil procedure in the United States is politicized, seemingly to a greater extent than in the EU. A more technical path toward procedural harmonization might be possible, and more desirable, in the EU.