Purchasing Train Tickets?

It depends on several factors. If you buy early (up to 120 days ahead) you can save some money but you lock yourself into a specific train. For total flexibility, buy in Europe. When are you going? There are two competing train companies that have high speed trains on the Rome to Naples route.
trenitalia.com and italotreno.it/en
To see what you would pay for a walk up fare, enter tomorrow as the date of travel. Then enter your actual travel dates and see what is available and see how much the price difference is. It's up to you to determine whether you want to be flexible or have a specific train at a specific time (nonrefundable).

On this route you can take trains by Trenitalia or by Italo.

There are three kinds of fares on Trenitalia (I think Italo is similar, but don't know for sure). Super Economy is the lowest, and is totally non-refundable and non-exchangeable; if you don't take the EXACT train you purchased tickets for, the ticket becomes scrap paper. Economy is not refundable, but if you change it before travel, you can apply the fare to the price of a new ticket (so you don't lose money). And Base fare is fully refundable and exchangeable.

Once a fare class sells out, it's gone and doesn't come back. Super Economy sells out first, then Economy. Base does not sell out until the train is completely full. The price does not go above Base fare - even for a last minute ticket purchase.

If you want cheap tickets and can live with the restrictions, book ahead for best shot at getting these. If you don't mind paying Base fare (which isn't that high) or want full flexibility, you can wait until you get to Italy. Your choice.

Note that once you have a ticket - bought in advance or on the day, bought on line or in person - you must take the exact train on your ticket (which comes with a specific seat reserved). If you want to take a different train, you must change your ticket BEFORE boarding - regardless of what you paid for it.

Look at Trenitalia http://www.trenitalia.com/tcom-en and Italo http://www.italotreno.it/en to see prices for your dates. Even on the English language websites, you need the Italian station names - Roma Termina and Napoli Centrale.

Thanks so much for the information! We will be travelling on Wednesday May 24th. From what I've read, we will be VERY careful about pickpockets in Naples Centrale train station. Price isn't a huge factor although, obviously, want to be as frugal as possible. Just want to make sure we get a ticket and a seat! Which train do you think is better?

Also, I was on the trenitalia website and saw a "senior" fare (we are over 60). It says you need a "cartaFreccia" card...is this something you buy in advance or only for Italian citizens or...?

Pickpockets need a crowd to approach distracted tourists without being noticed. Be careful when getting on/off the train, but they prefer to work on the unreserved and crowded commuters' trains to Pompeii and Sorrento rather than in camera controlled stations.

Everybody can purchase a Cartafreccia Senior, but it's a one year card and the cost is so high that you should do many more journeys to break-even.

There probably isn't any point in purchasing your train tickets on line at this late date because all the discounted fares are surely sold out.

To purchase tickets at the train station, you have two options - 1) a ticket vending machine, and 2) an attended ticket window. The last tie I was in Italy, I noticed fewer attended ticket windows than in the past an a couple smaller stations I went to there were none - only ticket machines.

The line for an attended window can be long so allow extra time if you want to go that route.

In order to use a ticket vending machine you need to use a credit card with a chip and you will need to know the PIN. If you don't know your PIN, call your bank IMMEDIATEY as it normally takes 10-14 days to have one mailed to you. (You may be lucky and your bank may allow you to select/change a PIN online but that is the exception and not the rule.)

If you are using a ticket vending machine, don't let people "shoulder-surf" and don't let that very innocent looking young man/woman who offers to assist you. The ticket machines are multi-language (look for the British Union Jack flag icon) and are pretty easy to use. Probably the biggest things to remember are 1) Italian city names, 2) Preferred rail station names, 3) type of train service (high-speed or regional), and 4) class of service. You might want to spend some time on the Trenitalia web site to orientate yourself.

The next thing to remember is ticket validation. If you purchase tickets on regional service, the tickets MUST be validated before you board the train. In the station lobby and on the platforms there are time clocks - stick the ticket into the slot and it will stamp the ticket with the date and time. If the conductor catches you with an un-validated ticket, it will be a huge fine. The rule of thumb is this - if the ticket lists a specific train number, carriage number and seat number, it does not need validation, if the ticket does not list a specific train number, carriage number and seat number - it does need validation.

Tickets purchased on-line do not need to be time-stamped, it doesn't make any difference if you have a specific train number, carriage number and seat number or not.

There is a reason to time-stamp only locally purchased regionale tickets: from the moment you validate you can get on any regionale train making that route for the following 4 hours. If you purchase on-line it's 4 hours from the departure of the train you booked on trenitalia.com/tcom-en.

In Liguria, the region where the Cinque terre villages are located, the 4 hours window is reduced to 75 minutes.

Such helpful information in this thread.
Much thanks!