The Enlightened Mind Movement was an organization that in 2347 began to strive for Betazed to leave the Federation. (Last Unicorn RPG module: All Our Yesterdays: The Time Travel Sourcebook)
The movement could be blamed for much of the prejudice against Betazoids and telepaths. The members actively used their telepathy without regard for privacy in the hopes to drive a wedge between Betazed and the Federation. The movement once plotted the assassination of Lwaxana Troi, but Starfleet Intelligence managed to stop it. (Last Unicorn RPG module: Planets of the UFP)