Can't speak for the US, but this is the case in Canada. I sponsored s.o. for their permanent resident visa and we were told to wait until the status has been a

Can't speak for the US, but this is the case in Canada. I sponsored s.o. for their permanent resident visa and we were told to wait until the status has been approved before any kind of work can be done. The immigration hotline mentioned that volunteer work would be possible during that time, but it would still require an application from the employer. It took the employer a few days to get all the paperwork sorted out and 2 weeks later the application was denied, leaving everyone a bit disappointed & furious about all the wasted time and promised opportunities on both sides. Generally speaking: even if you do work as a volunteer, the kind of work you're going to do is most likely s.th. that should either be paid for or could be done by a local resident/citizen. If the US system is anything like the Canadian one, then you'll still get in trouble if they figure out that you've been working, even if it's for free/volunteer work.