The action represents the largest number of lawsuits filed at one time since the trade group for the largest music labels, the Recording Industry Association of America, launched its controversial legal campaign last summer to cripple Internet music piracy.
Citing Internet addresses, music lawyers filed the newest cases against "John Doe" defendants and expected to work through the courts to learn their names and where they live.
The recording association said each person was illegally distributing an average of more than 800 songs online. Each defendant faces potential civil penalties or settlements that could cost them thousands of dollars.
The resumed legal campaign was intended to discourage music fans emboldened by last month's U.S. appeals decision, which dramatically increased the cost and effort to track computer users swapping songs online and sue them.
"Our campaign against illegal file sharers is not missing a beat," said Cary Sherman, president of the recording association. "The message to illegal file sharers should be as clear as ever."
All 532 lawsuits were filed in Washington and New York — home to Verizon Internet Services Inc. and Time Warner Inc. and a few other prominent Internet providers — although the recording association said it expects to discover through traditional subpoenas that these defendants live across the United States.