It plans to file several hundred lawsuits over the summer - sharply escalating the industry's battle against online piracy.
Internet service provider Earthlink said it had received three subpoenas since the RIAA pledged to track file-swapping sites such as Kazaa for heavy users.
Earthlink spokesman David Blumenthal said the company would go along with the order to identify individuals.
But he said: "We disagree with the method that is being used here and while we support the right of them to enforce copyrights, we think this is the wrong method for doing so.
"We're urging the RIAA and other copyright holders to find a less intrusive method for protecting their intellectual property."
The RIAA plans to use software robots to search for copyright violations, as well as sending warnings to universities and businesses demanding they remove illegal material.
It has already been disrupting the file-sharing networks with fake files of its own which contain white noise.