Typical Apparel in Rome

Italians love converse sneakers. Whether that's comfortable wearing walking all over a city with cobble stoned streets is up to your feet.

Wear what you are comfortable in, bearing in mind churches will want your knees and shoulders covered.

If you are in Rome you will be surrounded by tourists from 20 different countries as well as locals so you will see a hundred different clothing and footwear styles. Wear what is comfortable, just not too revealing particularly if visiting churches. I have seen sneakers, hiking shoes, walking sandals, dress sandals, flip flops even several girls in miniskirts and platform heels trying to negotiate the cobblestones. Just be comfortable and enjoy yourself.

Ditto to all of the above: wear what's familiar and comfortable. Easy-care fabrics which can be rinsed out and drip-dried overnight are helpful for reducing the amount of clothing to mess with, and keeping the weight in the luggage down. Try to pack pieces which can be mixed and matched, and don't pack anything you aren't absolutely sure you'll wear multiple times.

A lot of us leave the shorts at home because of the dress-code for churches/Vatican Museums and because they're not as common among locals in the cities but longer versions (knee-length; both men and women) are fine, and work for things like the Colosseum/Forum/Palatine on a brutally hot July day. Some women prefer skirts for staying cool.

Shoe styles are all over the place, and there's a difference between the tourist who will be spending hours and hours walking and a local who is going to work. I don't choose to wear sandals for sightseeing in Italy because I'm a klutz who will constantly be stubbing my toes on cobblestones, stairs (lots and lots of those) and uneven surfaces but some women do wear their favorites. Whatever is your preference, just make sure they are broken in and have a good tread. I would take at least one pair of closed-toe for rainy days.

Wear what you wear at home the most when it is really hot out. Chances are whatever you wear the most is the most comfortable thing you own. Except sandals, too many people and uneven, dirty streets for sandals IMO. You will see people dressed in every imaginable way so there is nothing "correct" to wear. You'll be hot and places will be crowded so think comfort, ease of washing (if possible) and something you can wear multiple times between washing. Take less than you think you need, it'll give you a reason to stop in the multitude of stores you will pass by if you need something else to wear. In the history of Rick Steves forum nobody has ever complained that they took too few articles of clothing.

I concur. Wear what you're comfortable in, especially shoes. Those cobblestones are hard on your feet. We went mid May to Rome & Venice and I wore slip on tennis style shoes in a neutral gray, black sandals and tan sandals, all well broken in & comfy. As far as clothes, it was pretty warm and I wore capris most days and usually a dress for dinner. My hubby only wore shorts a couple of times because of the churches. Mostly just don't worry about it. Be comfortable and have fun!

To avoid always having to smear yourself with sunblock, you can buy light colored long sleeve shirts with sunblock fabric at many travel stores. They also dry very quickly. Here's an example:
Craghoppers shirt

Rit also makes a solution that you can wash your clothes in that gives them an SPF through many future washings. Here it is on Amazon: Rit Sun Guard

For shoes, I like something with a very stiff sole because of all the cobblestones. Be sure that you've broken them in completely before you leave.

do not forget the pickpockets in Rome. I bought a day back pack from Pacsafe at zappos.com. it was a life saver, the zippers has clips and it had a metal mesh with wires. FYI.
Adolfo

I've never seen a man turned away from a church for wearing shorts, at least not typical shorts that are down to the knee. Many women carry a lightweight shawl/scarf to cover shoulders or wrap around the waist to make a skirt and cover their legs.
I always take a pair of shorts and wear them a lot when it's hot out.

I pack pretty light, so my typical touring outfit is a lightweight pair of slacks that look casual to dressy, decent shirt, usually button up, and good walking shoes, black or brown that "go" with everything I bring. For women, my wife usually wears slacks or a light, longer skirt. She will wear sandals if we are just going to dinner, otherwise she has a comfortable pair of flats she wears.

Lightweight clothes work great in the heat and dry easily, I too would stay away from flip flops and sandals, the streets are too rough and dirty.

I'm in my fourth week in Rome right now and I'm going to disagree with those who say to just wear whatever you're comfortable in. At least for men. It's true that, whatever you wear, you'll see people wearing worse. But that approach won't get you the best treatment.

People in Rome don't think it's normal to wear "workout" gear including running shoes, running shorts and lycra t-shirts for anything other than working out. And baseball hats are a definite sign that you're a tourist.

For men, wear a collared shirt and comfortable shoes that aren't running shoes. Can't speak to women's wear, but I definitely have seen people turned away from churches for wearing shorts or bared shoulders.

A story: One morning I rolled out of bed, pulled on my running stuff and stumbled down to the local bakery and the baker basically wouldn't serve me; he skipped straight to the woman behind me.

I am in Roma now. Some Capri pants on men, more on women. Tennis shoes are okay, cross-trainers are not. Every type of sandal on men and women, but the Birkenstocks are on tourists. Italian men and women in jeans (you know they're Italian because the jeans are tailored).

Shorts: mostly tourists in shorter shorts, although in smaller towns I've seen local teen girls in shorts (their moms were probably at work when the girls got dressed). Roma is a city, people tend to dress less casually than at the mall in the U.S.

Lots of sundresses for women.

I was there a few weeks ago with temps up to 29 degrees Celsius/88 Farenheit in the afternoon. I didn't notice any men, other than tourists, wearing shorts - most wore slim-style jeans or dress pants. A LOT of women were wearing summer dresses. No athletic-type sneakers but lots of Converse/Vans type sneakers. Local women wearing ballet flats or pretty sandals (not flip flop-style sandals). There was unquestionably a tendency for people to be more 'dressy' than in our North American cities. I took a pair of Puma ballet flats to wear (ballet flat style but sneaker comfort) with my dresses and capris. I took sneakers for walking but didn't wear them once, the Pumas were so comfortable and I loved that I could slip them off to cool my feet when I sat down. They were almost black when we came home 6 days later ... so make sure your shoes are comfortable but not so special that you will mind them getting really dirty.

That being said, chances are you are going to be doing a lot of walking and spending a lot of time in the sun. Comfort should be your first consideration.