Is there an on-line schedule for the commuter trains (Metroferro, the “FM” series) in Rome? I don’t find it on the Trenitalia site. Also, my two guidebooks tell me to take the FM3 from Flaminia to get to Viterbo, yet my train map shows the FM3 leaving from Sta. Ostiense and that the train from Flaminia to Viterbo is the F, not the FM3; which is correct?

Where exactly are you trying to get to? The SLOW commuter train to Viterbo, which runs directly few times daily (only at peak commuter times), does indeed depart rom Piazzale Flaminio. There is no online schedule that I've found, only a 2002 printed version, with errors, available at the station. I use that line alot. Another line, nicer trains, takes a more westerly route and does pass through Ostiense.

I am trying to make a daytrip from Rome to Viterbo. I am also hoping to travel from Fiumicino to Sta. Trastevere. Some one (I think it was Jim Z.) suggested that if your final destination is in the Campo dei Fiore-Piazza Navona area that you're better off taking the FM1 from the airport to Sta. Trastevere and then taking the #8 tram to your destination; this is a lot better than taking the train to Termini and then a combination of busses or taxis to your final destination. I am trying to get a schedule for both of these trains.

These are 2 separate trips, aren't they?

Anyway, yes, the train from FCO to Trastevere is a regular, and predictable thing, for which you should find an online schedule. I have taken it many times, and I believe it leaves at least once an hour or so, perhaps even twice an hour from the airport. It's also much cheaper than the train from Termini. He's right: the #8 tram is a great way to get into the center avoiding Termini from Stazione Trastevere. A day trip to Viterbo is going to take you a long time though. Going from Piazzale Flaminio, it takes 1 1/2 hours to get to Civita, the half-way point to Viterbo. Then it's another hour plus to get to Viterbo. I may have a schedule here in Seattle for the Viterbo (via Civita) line. What day of the week and what timeof day? I suggest you start out early!

BTW, the train route I mention to Viterbo is actually an ATAC train, not FS: www.atac.roma.it.
It looks as though your best bet is a Sunday trip! Departure from Flaminio 7am, arrives Viterbo 9:35 am. Later on Sundays and holidays only a departure from Flaminio at 9:30 arrives Viterbo 12:08. From my printed schedule, dated 2000 (just picked up in April), there are NO early morning weekday trains. The ATAC site may be the place to find the Ostiense train schedule. Failing that, a travel agent in Rome can easily and quickly organize tickets for you with at least 24 hours notice.

For going from the Airport to Trastevere, on the Trenitalia site you can fill in Roma Aeroporto and Roma Trastevere. They're also outlined here on the airport site; anything going to Tiburtina also goes to Trastevere, so they go every 15 minutes Mon-Sat, every 30 minutes on Sunday.

Edited to add: be aware that trains marked Leonardo Express going to Roma Termini do NOT stop at Trastevere.

no matter where you are in Rome, jump on the metro to Valle Aurelia. From there you can take the train to Viterbo (l each hour, leaving at 10 min to the hour) and arrive in 1 hr. 20 min. Cost of ticket is about 5,90. A round trip ticket valid for the day is 9 euro. If you can avoid peak hours, its better.
We who live in the Vetralla-Viterbo area use this line instead of taking the car into Rome, as a great way to leave the car at home, not pay for exorbitant parking in Rome, and have quick access to Rome's metro system.

Hello Mary Jane!

When will the new book be ready?

Since these trains don't allow reservations and don't require tickets to be bought in advance, you probably don't really need to check the schedule before your arrival in italy. Once in Rome, go to the ticket office and ask for the 1 euro local trains schedule book. It has timetables for the main railway lines as well as for local trains, and it is much cheaper than the big books for sale at newsstands.

According to a variety of train maps and the airport web site, the trains from Fiumicino to Tiburtina, Fara Sabina, and Orte all stop at Sta. Trastevere, is that correct?

As far as I know, that's correct. The trains listed in the four columns are all the same trains going into Rome; they just have different destinations beyond Rome. That is, the 5.57 to Tiburtina is the same as the 5.57 to Fara Sabina and Orte, and all these trains should stop at Trastevere.