The Organization for Economic Cooperation and Development is reducing its predicted global growth rate for this year, but expects growth to improve in many nations next year.
OECD experts say the global economy will expand 3.4 percent this year, slightly less than the previous projection.
The OECD is made up of 34 mostly wealthy nations with market-based economies.
The group's experts say China's growth will slow, though it still will reach a strong 7.4 percent. The study says the 18 nations that use the euro will expand a bit faster than first thought, with growth of 1.2 percent. US expansion will slow 0.3 percent to 2.6 percent for the year.
The OECD says the U.S. central bank is on the right track, keeping interest rates very low while gradually cutting back on other efforts to stimulate the economy.
The head of the U.S. Federal Reserve, Janet Yellen, is scheduled to give an updated assessment of the U.S. economy on Wednesday at a congressional hearing.