Dressing my kids for Paris/France

You didn't mention what part of France you will be visiting, but I would begin by bringing something comfortable for quite hot temperatures and jean-type cooler weather, something that washes easily, light weight fleece for the airplane and as a wrap. If they like to shop, let them buy something new while you are there. I wouldn't worry about it too much. My kids made friends with an NFL t-shirt, something I would have been inclined to leave at home.

Ideally...yes, shirts without words (solids, prints, stripes, whatever) and shorts or capri pants or skirts. BUT traveling with kids is hard and if wearing silly tween fashion makes it easier...my advice is to let it go. It's not worth the battle, unless you are going somewhere with an actual dress code. I'm sure French kids are wearing jean shorts - they are in right now.

we will be in Paris for several days and then basically in smaller cities and the countryside. they are not big shoppers. I will take the advice of a few plain colored shirts for dinners out and a nicer pair of capris/shorts. thanks.

You could always begin the negotiations by insisting on the frilly dresses and patent leather shoes, and then concede down to the nicer shorts and plain shirts. I'd be inclined to let them wear mostly what they want, as long as it was weather appropriate, and they carried their own stuff.

I have taken teen boys to Paris and other cities, and while they tend to dress like Americans when home, they found it fun to 'up' the style a bit while in Europe. They won't see anyone they know, so they can buy some European stylish clothes that they might feel comfortable wearing. Adorable sundresses, boho style clothes, etc. might interest them.

I don't know if the style of shorts is as important that they actually provide "coverage." I saw several American teenagers that stood out like a sore thumb because of their immodest dress last summer.

I agree with Emma on the slogan t-shirts---assuming they are not off-color or rude ( which I assume you would not buy for your daughters).

You may see Asian teens in T-shirts with all kinds of slogans, in English---many of which will make no sense.

If they wear those clothes at home, why would it be any different in France? My 11 year old wears logo shirts as do all their classmates. Pretty normal here in Austria, but ask yourself - does anyone notice or care what young girls are wearing? I'm sure they will be fine with whatever they choose.

I've see plenty of teenage kids in Europe with logo shirts, shorts, the same kinds of things I've seen kids wear here in southern California, especially if it's hot in the summer.
Just avoid showing too much skin unless you're headed down to the Paris plage. Beach/athletic wear really isn't acceptable out on the street. If you'll be visiting churches or museums they should tone it down a bit. In big cities tourists from all over the world dress in a million different ways with a huge variety of styles - everyone there is used to it. In smaller places that aren't as used to tourists you may get some looks but I wouldn't worry too much about it. It's their behavior that is the most important thing

I will bet you that those slogan tees are the height of haute couture on the streets of Paris for girls their age.
Now, for dinner at le tour d'argent, that's a different story.
We'll have my 14 yo daughter (she'll turn 15 while we are there) and 11 yo son in Paris for 2 weeks this June.
I'm already bracing for the struggle sure to ensue when I tell the boy he will need a sport coat for several evenings.

I suspect it would be easier for girls; I bet a few reasonably-priced (I hope this is a thing) parisian shopping trips will solve the too-casual issue.

No sport coat needed for anyone unless you go to a ritzy restaurant etc. Cut-offs and ripped jeans are not popular. Too much skin or make-up are also no-no's . Hairstyles very simple . Mostly practical walking shoes . There will be so many tourists with different styles , I would not worry. Got back from France last night so this should be up to date .

In general I'd say there are no holds barred for young children. People probably won't think twice about cut off shorts and t-shirts with words on them. Your girls, however, are getting to an age where they might care.

I'd say your biggest issue is to get the girls to wear shoes that will work for lots of walking. If they have a comfortable pair of sneakers they wear most of the time now, bring those as the main shoes for the trip. Don't let them think a pair of flip-flops will suffice.

I think it would be nice to have something that's a little nicer, for dinner or to visit a church, but you're probably better off pulling something out of their current closet selections than trying to get them to pick something entirely new. A nice pair of capris, plain shirt, light-weight sweater, and ballet flats would be more than nice enough. Tell them they need to pack at least one nice outfit for nice restaurants or churches and see what they come up with. You may get there and find something they really like in a department store or boutique; if so, that's even better (but I'd still pack at least one nice outfit).

When it's hot, people of all ages in France wear shorts and T-shirts - slogans are absolutely fine, as long as they don't insult anyone.
Cut-off jeans will really be too hot, so some lighter fabric would be best. If going to a church, you might not be allowed in if wearing tank-tops or tube-tops, so bring something to cover up with if going there.

On the other hand, it might rain, and sometimes it can turn chilly at the drop of a hat. One pair of capris wouldn't hurt, and a light windbreaker would come in handy, too. Jeans will be too heavy in your luggage, and they probably won't get to wear them.

Ballet flats are a bad idea unless you're just sitting down eating dinner and don't have to walk anywhere. Most people wear sneakers everywhere - the more outrageous the color, the better. Sandals will be cooler, but your feet will be filthy at the end of the day, and might not be too comfortable.