I am not an expert but when I bought a Navigo Decouverte, I brought my own photo (the size photo is given somewhere - about 1 - 1 1/2" square). You purchase the card in the machine and the lady at the window in the Metro station made the card for me in a plastic holder. I've since used it a second year and reloaded it at the machine. You do not need to get a new one each time or each year - it is a re-loadable card. I will be returning this spring and reusing the same card.

Thank you so much for the info. I hope you enjoy your trip.

The official photo size requirement is 25mm x 30mm. The card itself

You can of course purchase a ND at CDG but it is unlikely you will want to use it then if you are only going to be in central Paris where the ND price per week is 19.80€. To include CDG to Paris will cost 34.40€

Thank you Sarastro.
I figured that it would cost more than $18 to get from CDG by RER or Air France bus, or $10 for Roissy bus, so I might be better off buying the more expensive one.
I also plan to go to Versailles and Disneyland,at some point,and that would be included in the more expensive one.

You can definitely bring your own photo, and I recommend doing so. There are not photo machines at all stations and even when there is one there's no guarantee that it will be in service. (Learned this the hard way!) No need for a fancy pic - you need just a face shot and can use a digital photo you have on your computer, print it out in the size you need on regular paper. I just measured the pic on my own Navigo and it is 1" wide x 1.25" high, slightly smaller than a US passport photo.

You do not need a new picture each week, though you will have to buy a new pass each week. What you will be buying (for a one time cost of 5€) is a little "kit" which contains the plastic Navigo card and accompanying paper identity card on which you enter your name and affix the photo using the supplied laminating material. The plastic pass and the paper ID card bear a matching serial number. Both slide into the clear plastic holder which is also in the kit. You will then be able to "load" or electronically charge the card with a pass for zones 1-2 at a cost of 19.80€ per week which starts on Monday and ends on Sunday and not a floating seven day period. You can buy the kit with the cards anytime but the weekly pass is only sold until Thursday of the week in which it is valid. Weekly passes bought on Friday, Saturday or Sunday are valid beginning the following Monday. You can continue to use the same card - that is, load it with a pas for additional weeks - for several years.

It is not worth buying the more expensive weekly pass just to get into central Paris from CDG. The RER fare is only 9.50€ If you hunt around you will find lots of opinions about whether or not the pass is a good deal. I find that it is, not just cost-wise but in terms of not having to keep track of paper tickets and being able to jump on and off buses as fancy strikes.

Thank you Seamus. This is great information. We like the idea of having the freedom to just go to any zone on a whim, and since Versailles and Disney are on the schedule, we plan to buy the more expensive pass.
I am still a little nervous about taking the RER with luggage (not too much, but probably one large bag and one carryon). Is there room to store a large bag, close enough to keep an eye on it? I imagine bleary-eyed arrivals are fair game for would-be thieves. Our apt is near the Pompidou Center, so we am thinking of taking the RER B to Chatelet/Les Halles and then a taxi to the apt. I don't think I want to do the subway stairs with so much luggage. Thanks again for all the suggestions.

If there are two of you, cost is not the primary concern, and you are concerned about being a vulnerable bleary eyed tourist on public transport, why not just take a cab from CDG to the apartment? It's what I would do. Easy peasy - when you exit customs just walk out the door to the curbside taxi rank. Do not accept any offers from rogue drivers, only use licensed taxis available at the official taxi rank.

harvmatic, as long as you're not on the RER at morning rush hour, there should be plenty of room for you and your luggage. It's a fairly spacious train; not as crowded as a Métro car usually is. I don't recall if there are luggage racks except for the overhead bins, but you can set bags on the seat or floor next to you.

Les Halles is a pedestrian area, so you'll have to walk a block or two to get to a cab -- and by then, you'll probably be only a couple of blocks away from Pompidou. Check a map online (look up the RATP site, www.ratp.fr) to get oriented.

If you can get in a nap before heading to the airport, or can rest reasonably on the plane, then the excitement of being in Paris should keep you fairly alert during the trip in. It's an interesting ride; you get to see some of the Paris suburbs before the train goes underground. And a stroll from Les Halles along rue Rambuteau should be refreshing, also. Move along purposefully, and you shouldn't be bothered by would-be thieves. We've never been!

Thank you all for all the wonderful information. One more question concerning travel and disabled persons. I will have such a person visiting me for a week (from Ireland, an EU country) and wondered if she qualifies for any reduction on train travel in France. I know all the museums offer free or reduced admission to disabled persons, but I haven't come across anything regarding travel reductions.Any information on this would be much appreciated.

There isn't any special place to store luggage on the RER, that's one reason I don't like it. There are just some very small overhead rages for a small daypack or something, but you couldn't fit any size suitcase up there and there is no place on the cars for luggage otherwise. So the only hope is if the train isn't crowded, which should work if you get on at CDG.

I don't think you get any train reductions for being disabled unless you have an official card from the French govt, because that verifies what the limitation is (and then it must be 80 pct). It is called a "carte d'invalidite". I don't know if the person you know has the equivalent in their country to show, maybe that would work, if not, it isn't just because someone says they are or even if they are in a wheelchair (which could be bogus or temporary).

For free or reduced museum admission - The person must have "official" "documentation that the person is disabled and if it is in a language other than French ,that could be an issue. Some museums are more accepting than others.

One other thing. The cost of all zones 1-5 vs 1-2 is almost 15€ more per week. Why would you pay 45€ - about $60 more for the 1-5 zones for the 3 weeks for only the ride to/from CDG, Versailles and Disney? Seems a bit silly to me. And keep in mind depending on your arrival day, you might end up buying 4 weeks of fare to cover partial week for first and last week if you arrive AFTER Monday and leave AFTER Monday.

We plan to travel to all the outlying areas where the trains go, so we will be making full use of our zone 1-5 ticket. Thanks for all the recommendations. I am curious as to how the Navigo D works in the metro. It is obviously larger than the average metro ticket, so does it need to be inserted in a different slot, or swiped against some type machine?. Also, how do I use it on a local bus?

Swiped, both for metro and bus.

"You do not need a new picture each week, though you will have to buy a new pass each week"

You do not BUY a new pass each week, you simply recharge it, using the same plastic pass and picture that you first buy.

I was going to comment on that also, you really don't buy a new pass every week, which is the main plastic gizmo with photo. It's electronic, you obviously have to swipe it against a sensor. This is pretty common for lots of cities now to have reloadable electronic cards for transportation, which you pass over a sensor when entering the system and reload each week with a dollar amount.

Language / semantics, I think. In my post I tried to distinguish between the plastic and accompanying paper cards and the electronic pass. The cards are a one time purchase, the pass must be re-purchased for each week of use. We have been using the same card for several years now, just purchase a weekly pass when we need it during our too infrequent visits to Paris. Apologies for any confusion!

Good to know. Thank you all.

My husband and I will be arriving at CDG, from the US on a United flighy, at 7am and would like to take the time to have a decent breakfast, if possible and avoid the morning rush hour, before taking the RER B into Paris. Is there a place in the terminal area to have a decent breakfast, or at least a good cup of coffee and a croissant, before continuing our journey. I would appreciate any info on what gate we will be arriving at, and if we have to take a shuttle to where we need to go to board the train. Also, what time is considered "morning rush hour" in Paris?

Think you are worrying needlessly. Paris starts later than US cities and you will likely get into town just fine, whereas if you tried to wait out the am rush you'd have to sit for a couple hours in a lousy airport boite, feeling the onset of jet lag. You'll arrive on United at Terminal 1, not exactly a hotbed of fine dining. IMHO, you're probably best off just grabbing a coffee and croissant at Brioche Dorée on your way to the RER. There is one on the lower level where you pick up the CDGVAL to get to the RER station. The arrival adrenaline and a cuppa will keep you going. Plus, the train (RER) you will take originates at the airport so will be nearly empty when you board.

Thank you Seamus.
one more question. Does the RER arrive at street level at RER station Chatelet-Les Halles, or would there be stairs/escalators involved to get to street level for a taxi ?
I think I am leaning towards a shuttle, or perhaps a car service, for convenience sake.
Thanks for your help.

No RER train in Paris is at street level that I can think of, it is an underground system within the city. IN any case, it definitely is underground at Chatelet-Les Halles, real underground. There are trams in Paris that are at street level, one goes around the outer edge in the south that I use sometimes.

Thank you Christina. That settles it. Now it's a decision between shuttle or private car or taxi. I am shying away from taxi, due to the possibility of incurring enormous charges if there is a traffic jam, and the meter continues to run. I used a shuttle last year, and it was fine, but it was arranged by the hotel and I don't know what is was called. I read one bad review of Shuttle Inter.........didn't show up and never apologized. Any suggestions would be appreciated. Thanks.

harvmatic, you really need to relax a bit. Just walk outside the terminal to the taxi rank and get a cab. The chances of an enormous traffic jam are incredibly remote. Count on about 50 - 60 euro door to door and you will be fine. A shuttle will not be much, if any, less and quite possibly more.

Thank you Seamus, but I like to shop around and get the best deal. As seniors, we have to budget where we can. Has anyone used Viator from CDG to Paris, recently? They seem to be the most reasonably priced, but price is not my only concern. I have read some negative comments on Shuttle Inter, but I realize that anyone could have one bad experience with any service. Any help is appreciated.

Since you will be there for 3 weeks, and none of us wants to spend more than necessary, think about buying the zones 1-2 or 1-3 for one or two of the weeks and the more comprehensive for the week or weeks your plans call for being away from the center.

We have returned from our trip and thanks to all for your wonderful tips re the Navigo Decouverte and the shuttle from CDG.
WE booked online with Super Shuttle and they were there to meet us and called our apt manager, when my phone was temporarily not working. I highly recommend them for clean, comfortable and prompt service and at 43 Euro for 2 people, a real bargain. I had booked and prepaid online, so saved my euros for the tip etc.
The Navigo card was fantastic. We purchased the one for all 5 zones and went everywhere on it, for 1 week. We even took the RER back to CDG when we left Paris a week later to go to Ireland(long story !)
Thanks to all perhaps for your recommendations.

thanks for the follow-up as to how things worked out. So how did the RER trip work going back to CDG? Was it easy for you and are you glad you took it or not? How far did you have to go to get to the RER, it sounds like you couldn't walk to the RER, what did you do.