buying eurostar passes between Paris and Berne

I would ( and do) just wait till they are for sale on Eurostar.. if you want to save money, if you want to pay more just to have a ticket in hand ( which I also don't do) then have you looked at RailEurope, they usually ( but not always ) charge more, but they also do not show the full schedule, so if you don't see a departure you like you'd be better to wait.. you lose nothing by waiting.

To add to what you've already gotten from Pat and Nigel: To find schedules between Paris and Berne, look at http://fahrplan.sbb.ch/bin/query.exe/en (Swiss rail). The schedules for July are not yet loaded, but look at something in May for the same day of the week you will be traveling, just to get a sense of the options. You won't be able to buy tickets for your dates until the schedules are posted. Don't worry - nobody else can buy them either. You should start looking 90 days before your travel, and then buy them as soon as they are posted, so you get the best prices. To buy your tickets, you would look at the above site, or at http://www.tgv-europe.com/ (French rail). If you are using French rail, choose Great Britain as your country, and resist all attempts to be redirected to Rail Europe. I'm not sure if French or Swiss rail would have cheaper tickets. If you use Swiss rail, make sure you are getting an e-ticket; you won't be able to pick it up in Switzerland (this will not be a problem if you use French rail, as you'll be able to pick it up in France). If this is the only train you're taking, you definitely don't want or need a pass. But depending on what you're seeing in Switzerland, a pass just for that country may definitely be a good investment. Post more details of your itinerary here, so others can help you choose the best one (figuring the options is complicated).

I'm afraid that Eurostar won't be able to help you. Their trains don't go there. Eurostar only connects London with Paris and Brussels, with seasonal add-ons which go to the French ski resorts and Avignon. Eurostar Italia is limited to the main core routes of Italy. Neither go into Switzerland. You will travel on French TGV trains from a Paris station to either Geneva, Lausanne, or Basel; or to Strasbourg in France with a connection in Strasbourg to a regional and a connection in Basel to a Swiss train. You say you want a pass? Or do you mean a ticket?

marlene, As mentioned in the previous reply, a Railpass may not be the best option if the only journey you're taking is from Paris to Bern. However, if you'll be travelling elsewhere in Europe and decide that a Railpass would be worthwhile, you can buy it from this website (click the Railpasses tab at the top). You could also call the ETBD Rail department for advice, as they'll be able to provide all the answers. Happy travels!