My wife and I just returned from Italy, Spain, France and the UK. I don’t see any reason why it wouldn’t be safe for you there. You should just take the same precautions you would on any trip.
Check out the Safety Travel Tips on the board here.

You’ll be fine on your own and I think staying in private rooms in hostels will be a good choice. Read lots of hostel reviews and look into HI hostels as they are sometimes frequented by school and youth club groups of young teens and tweens which will give your daughter a chance to meet some kids — and practice language skills. The 18 to 28 crowd at obvious party hostels won’t necessarily be a bad thing, but might not be a lot of fun (or might be too much “fun”) for a 12 year old.

Suggestions:
1. Let your daughter navigate at least part of the time — figure how to use the rail pass, take the subway to the sights you want to see, find the hostel, buy the transit passes, find the Mona Lisa, etc.
2. A tip from my Mother that I wished I’d paid more attention to with my son…. Make your own “must sees” and “want tos” the main focus of the trip. Your daughter can always go back in a few years on her own. Let your daughter pick a few things she wants to see and do, but do not make the whole trip about her.
3. Do some non-sightseeing things like spend a day at the local sports complex swimming pool (where you might meet kids), people watch at a park, hike for a day in the Alps. Castles, museums, ruins and cathedrals get old — even for those of us who absolutely love castles, museums, ruins and cathedrals.
4. If your daughter is involved in any groups like Girl Scouts, find out about their European locales and activities in advance to see if something fits into your trip.

Thank you so much for your replys. special thanks to Old Lady for wonderful tips.

I usually recommend arming your teen with a transit pass, a map (with subway map), phone card (and the knowledge of where and how to use it) or cell phone, address and phone # of hostel (and it’s location marked on the map) and a little cash and letting them explore some in Paris on there own for a 1/2 day or so. 12 seems a little young for totally solo, but maybe with a friend? See how you (and she — my son would not have been comfortable on a solo excursion at 12) feel after you’ve been there a few days.

Where in Hawaii — if your daughter has navigated the bus system in Honolulu, the Paris metro will be a breeze.

I wouldn’t get separate rooms.

when are you traveling? My 13 year old daugther wants to see Italy (and where ever else I can figure out cost effective travel to within our alloted time off from school 9 days + maybe few extra) feb 17… I have been to Italy but she has not… I am finding flights very expensive from New York even in off peak season of February. Any suggestions?

Stacystuff: The original post is well over a year old, so the trip is probably over. Cocomaria hasn’t been active on the site since July of 2010.

Stacy, check out our cheap flights forum next-door for flight strategies.