Originally Posted by
swiftaw
. . . I am a UK citizen that lives in the US and I will (hopefully) also soon be a US citizen. . .
You cannot keep your other citizenships if you naturalize in the US. You have to renounce them.
Of course, DHS and DoS almost never check, so this is hardly ever enforced. However, if you're employed in certain fields (politics, legal, etc.), it's highly advisable to play by the book.
That is true - the US will require that you renounce. However, if you are a UK citizen they consider that to be a renouncement under duress which is ineffective. It is possible to maintain your UK citizenship. Not something they will tell you how to do - but possible.