Hello!
I recently posted last month to share my N400 Interview Experience, so thought I'd follow up now that I've gotten my Oath Ceremony out of the way and am officially a US citizen!
Main points to note
Guests - we were permitted to attend, however, from what I could see I would advise against it - the guests were told to sit at the back of the room and there wasn't a great view of the ceremony from that area
Additionally, the ceremony lasted all of 10 minutes yet took nearly an hour for everyone to be checked-in and seated - for that reason alone it doesn't seem worthwhile to bring them, but totally understand some people were fine with this and just wanted their loved ones in attendance
Oath Ceremony Questionnaire - I completed and signed this prior to the event. There has been questions about needing to do it in front of a USCIS officer, but from what I could see they had everyone that hadn't filled it out prior to arriving do so before they could join the check-in line, so recommend doing it in advance to save yourself time
Arrival - I recommend turning up no earlier than 30-40 minutes before the ceremony. I arrived 45 minutes early and despite breezing through security and up to the third floor, was sent back down to the lobby to wait an additional 10 minutes before they'd check me in
Dress Code - despite the recommendation to dress appropriately, I did notice a lot of people in jeans and sneakers.. I also observed a couple of guests wearing sweat pants! I dressed according to instruction, but seems that they were fairly lax about what people were wearing
Naturalization Certificate - this featured a photo of myself from a previous biometrics appointment (I recognized the shirt I was wearing that I incidentally no longer own). I was glad they had this on file as I had heard mixed advice on bringing your own photos as back-up
Oath Ceremony
The check-in line (where you provide your questionnaire to the officer along with green card, etc.) took around 20 mins of waiting before I made it to the front. I handed over my green card, EAD card, and questionnaire. The USCIS officer asked if anything had changed that would prevent me from completing the oath, e.g., divorce, arrests, etc. I replied no, and they took my documents and handed over my Naturalization Certificate and congratulated me! I was then directed to a seat where there was a couple of envelopes that had passport application, details on registering to vote, a letter from POTUS, the mini flag, etc.
It took a ton of time for them to check-in and seat everyone (an additional 30 mins!) so I busied myself reading the documents provided. Finally the time came to do the ceremony - they had us all stand, raise our right hand and wave our mini flags in our left hand as we recited the oath that the USCIS person read out for us to repeat. After that we were seated again and they proceeded to provide us additional information on registering to vote, applying for a passport, updating SS details, etc. They allowed for photos to be taken after the ceremony, but instructed attendees and their guests to do so on the second floor where an area had been setup for them.
After that we were permitted to leave row by row. It was super quick to get out of the building, which was a relief as I was concerned it would take longer! Overall, the USCIS staff were super helpful and friendly - tons of smiles, congratulatory wishes, etc.
I hope this provides some insight into the process - good luck to those of you who have yet to complete this stage! If you have any questions, do not hesitate to reach out.