How do I transfer my registration from a sold car to a car I bought thru a private party?

In massachusetts you cannot transfer a registration without an rmv1 form, you'll first have to switch your insurance to the car you bought and you will have to take the title and previous registration to the registry of motor vehicles, and they will do it for you. You can also have it done by your insurance company if they offer that service, some insurance companies have an on-site registration transfer, so you should call them first.

You will have to do it online through the RMV website .