No, the Eurail Pass does not work on the Paris Metro. The Paris Metro is operated by the RATP (the local city transit authority), while Eurail passes are valid for travel on the national rail network (SNCF). This means your pass will not get you through the turnstiles for any numbered Metro line (1–14). However, there is a slight overlap with the RER suburban trains. Your Eurail pass is valid on RER lines, but only on the sections operated by SNCF. Specifically, this includes most of RER Line C, D, and E. It is generally not valid on RER Lines A and B unless they are on specific national routes. Because the RER and Metro systems share many stations, it can be confusing. For travel within the city center of Paris, it is usually more efficient and less stressful to simply purchase a local "Navigo" pass or a pack of tickets rather than trying to use your Eurail travel day for a short cross-town journey that is likely not covered by the pass.