The League, first called the Citizens Survey Committee, was founded in 1934 by four members of the Marin Garden Club: Caroline Sealy Livermore, Sepha Evers, Portia Forbes, and Helen Van Pelt.
The Golden Gate Bridge was being built, and they worried about the increased automobile traffic and privatization of public land.
Their stated goal was "to preserve, protect, and enhance the natural assets of Marin County for all people."
Their early projects included working with the Tamalpais Conservation Club to add 531 acres to Mount Tamalpais State Park, helping to buy 54 acres at Drakes Bay Beach, raising $20,000 to buy a portion of Stinson Beach, and aiding in the creation of Samuel P. Taylor State Park.
[1] They also added land to Muir Woods, prevented Bolinas Lagoon from being turned into a harbor, and stopped Richardson Bay from being filled in.