There is no dress code for people who come to interview for a job at Facebook. I am curious, was something vaguely worded in an email you've received? Please let me know.
I came in in jeans, t-shirt, and a sweat-shirt. This applies to all Silicon Valley companies: wear whatever you're comfortable interviewing in.
One of the previous I worked for used to say "dress casually" (meaning "you don't need to wear a suit"), but we noticed that people have began to interpret it as "wear business casual" and have been reacting strangely.
Clearly, he is.
I'd imagine most of his employees don't get to hop on the private jet whenever they feel like it, either.
just because they havent told doesn't necessarily mean you shouldnt have your own sense as of what to wear to work. if that would be me, and not seeing anyone how they really look at work inside fb, i would came with suit and tie and figure things out the first day.
After all when all the non-conformist looks differently the same way, you need to do something different to stand out.
And I have a pretty good sense of what to wear to work in the valley. Suit and tie is the wrong answer.