It's raised its benchmark deposit rate by 0.75% — to 0.75% — and may raise further. But Europe is also facing recession worries.
As borrowing costs rise across the 19 nations that use the euro, worries about the currency bloc's stability grow.
It'll also end its large-scale bond-buying program. Central bankers are trying to tame inflation — like their U.S. counterparts at the Federal Reserve.
Until the ECB became the first major central bank to try it, making interest rates negative seemed like defying economic gravity.
The departing head of the European Central Bank vowed in 2012 to "do whatever it takes" to save the euro.
To begin with, the mandates for both are different.