Privacy advocates urge the search giant to follow standard industry practices.
Google has so far resisted the call for the privacy link, saying it did not want to clutter its homepage.
The organizations signing the letter include EPIC (Electronic Privacy Information Center), Privacy Rights Clearinghouse, the World Privacy Forum, Consumer Action, the EFF (Electronic Frontier Foundation), the ACLU of Northern California and the Consumer Federation of California.
"This is not rocket science. And the word 'privacy' is not going to take up a lot of space on the Google homepage," Marc Rotenberg, EPIC's executive director, said in a statement.
The spokesperson said Google not only offers a privacy center page, but also has created a YouTube privacy channel explaining the company's privacy policies.