What affects the exchange rate of a country’s currency? The answer depends on where that country stands in the world economy. Not simply because an exchange rate is the value of one currency versus another, so that you must weigh up two or more countries. It is mainly because the capitalist world economy acts both as a force that bears down upon everyone and because the most powerful countries within the system also have the most influence over how this works. Exchange rate theories ignore this latter point and this prevents an understanding of imperialism today.