When do I need to go through customs/immigration, and how long does this typically take?

The time spent in customs and passport control can vary based on time of day, day of the week, and seasonality. There is no flat answer.

You will do a passport control on arrival in Amsterdam. You will likely have to do a landing card on the plane, or in the line. Since you are flying from Schengen to Schengen on your next segment, the Amsterdam-Florence will be treated like a domestic flight, with no passport control or customs.

On your return, Geneva to Paris is like a domestic flight. Paris to Boston will involve US customs and passports. Customs will likely involve an ATM type transaction, and then a brief interview based on your responses to the ATM. Passport will involve a line and a rubber stamp.

As I said, the lines for these can vary. US international flights recommend arriving at the airport 3 hours ahead of departure. You might check in Europe. I was at Malpensa nearly 4 hours ahead of departure, but they don't check anyone in for the flight until 2 hours, so we spent some time at an airport, away from the fantastic duty free in Milan. sad. That might be an Aer Lingus specific thing. But check the local airport or with the airline to see how early you should arrive.

Hannah, No need to apologize at all. Things do change and even experienced travelers need to update from time to time about any number of things. Feel free to ask away -- we were all "newbies" once and had to ask for guidance. Max is correct in that there isn't any hard and fast answer. Wish someone had an easy way to determine the time involved, but there are just too many variables. Just plan on the process taking longer than anticipated and if it takes less you're simply ahead of the game.

Customs, except for the US, is always a walk through the Green Door - Nothing to Declare. Immigration/Passport control can take from 15 minutes to 2 hours just depending on the number of flights being processed, number of officers on duty, etc. If you have Global Entry your return to the US will be very quick.

I don't know the exact situation at Schiphol, but many big airports now do screening of carry-on items in a central area that will have line-ups and require inspecting your documents. In an era of security consciousness, your passport may be scrutinized several times. It almost certainly will be needed along with your boarding pass to enter the second airplane. Why worry? It's routine as long a you are not in a rush. You can explain all this to your parents but I suspect it's not procedures that are on their mind as much as you leaving them. Just go; that's life.

On the Boston-Amsterdam-Florence leg, you'll encounter Passport Control first thing after you exit the plane in Amsterdam. They stamp your passport and then you go on to baggage claim or your connecting flight. The length of this line depends on when you exit your plane. I've always found the line to go fast. On occasion, but IME rare, two international flights will unload at the same time and clog the Passport Control area, making the lines a little bit longer. No big deal.

On the Geneva-Paris-Boston leg, since you are a U.S. resident, you'll need to visit Passport Control first in Boston and then visit Customs after you collect your luggage. These lines can vary in length due to many factors. Global Entry members do save time.

Is the original question written correctly? The routes look a bit pointless. Are there stays in Amsterdam and Paris rather than simply connections - because that will affect how you pass through the airports.

I have relatives who regularly connect at Amsterdam and say it is efficient - except for transferring bags on tight connections. There was a report on the forum about CDG within the last few weeks from someone who was very impressed.

And if you are staying in Paris, why fly from Geneva, most people going city to city would use the train.

I guess I should've articulated myself better. I am traveling from Boston to Florence with a layover in Amsterdam. For my return, I am traveling from Geneva to Boston with a layover in Paris. I am also going to be in Europe for about a month, on an abroad trip with the class. Hope this helps clarify what I originally posted.

LOL! I went through Customs at O'Hare Airport before boarding Turkish Airlines to Rome. The Airline staff vanished and all of a sudden there were two USA Customs Police doing the final check of our documents before we boarded the plane. It was going to Istanbul, so maybe that's why, I don't know.

It was my first time on Turkish Airlines and my first time going through Customs Police before leaving O'Hare. We had to form two lines and take turns standing in front of the Customs Police at the head of our line. I always show both of my Passports at O'Hare, especially important this time cause I had a one - way ticket. Some people did not make it on the plane.

Hannah, this isn't your question, but I will just add that if you are in charge of booking your own airfare, make sure to give yourself enough time in Amsterdam to go thru passport control and change planes. If you can give yourself a 3 hour space between your arriving flight and your departure to Florence that is good. You can probably get by with less time but it may be a little stressful. If you are traveling with a school group then maybe they are organizing your tickets and you don't have much choice.

By the way, English is widely spoken at the Amsterdam airport so if you are on your own you'll not have any problems if you need to ask for direction.

I would also have maybe 100 Euro ahead of time in case you have time to get something to eat in Amsterdam. Or in case you need to buy a souvenir! There are tons of shops in that airport if you have time!

Have a wonderful time! Make yourself do a quick journal entry every. single. day. You think you will remember everything but you'll be having so many new experiences you won't!

Hannah,
I fly out of Boston. Flying out of Boston I've been in security lines for as little as 2 minutes to as much as an hour. Sometimes the global entry line is longer than the regular lines. Watch for a bit to see if any line is moving faster. Last fall, there were also sniffer dogs prior to the ticket and passport check to get to the gate. Just leave yourself plenty of time. Passport control in Europe can be long or short. No way of knowing ahead of time. Customs is a breeze.

Flying back to Boston I've encountered additional security checks at gate check-in in Zurich and Munich. I haven't flown back to the US from Paris but I would expect the same kind of additional security in Paris. Again, make sure you have plenty of time.

In Boston, there is usually always a long line for Passport control ( tend to get into Boston before 7pm so I can catch a bus to VT.) I give myself 45" to 1 hr for Passport control in Boston. I usually still have to wait for luggage before hitting Customs but I check my bag (a 22" spinner). Customs is generally not an issue unless you are selected for a search. I have no idea who or why the Customs people select the people to search.

Hope this helps and have fun!