Is it necessary for my nanny to be a u.s. resident?

No: This could be a tricky question that the federal eeoc would be happy to answer for you. However, a nanny could be here on a work visa, or an au pair from another country looking for an experience here in the United States. The essential thing is that they should be here legally to avoid future trouble. However, you need to make sure that your nanny is somebody you trust to leave children with.

See below: There is a legal requirement that anyone working in the us either be a citizen or have some form of work visa. This could be a green card or other type of visa. There are of course plenty of people who do not pay attention to this. If you are concerned you should talk to your attorney.