I walked with my daughter from StJPP to Santiago this past June/July 2010. She's older than your daughter; she just graduated from high-school. She wasn't really that keen on walking! She wanted to go to Spain, sure, but very few teenagers really want to walk 18 miles/day! All in all, she did fine, not great, but fine. Some days were harder than others, depending upon her mood, her blisters, the weather or the company! (She was great when there were other youngins around.) Having said all that, the last two weeks we walked with a Spanish father, his 13 year old son and his 24 yr old niece. The young boy did awesome. They were much slower than us, but we would always try to save them a beds near us in the albergue, and they would always show up an hour or so after us. He would come out with us to the cafes and the restaurants. We loved having him around; it was all in his attitude. He was chatty and outgoing, and we never heard him complain once. So I think the bottom line is that is really up to the individual kid. By the way, when my daughter did finish, she had quite a change of attitude. I think she realized what a feat she had accomplished, and now she's quite proud of her Camino. So definitely go for it. In the end, you won't regret it.