The festival was organized by Tom Rounds, program director of KFRC 610, San Francisco's powerhouse Top 40 AM station. KFRC's influence in the music industry gave Rounds access to both counterculture and commercial acts, producing a lineup that captured the era's eclecticism: the Doors and Dionne Warwick, Jefferson Airplane and the 5th Dimension, Captain Beefheart and the Grass Roots, Country Joe and the Fish and the Byrds with Hugh Masekela sitting in on trumpet. The festival was originally scheduled for June 3 and 4 as a benefit for the Hunters Point Child Care Center in San Francisco, but was postponed a week by bad weather. Several acts booked for the original dates could not make the new ones. All proceeds from the two-dollar tickets were donated to the center.

Panoramic Highway was closed to traffic, so organizers chartered school buses to shuttle everyone from Mill Valley to the amphitheater. "We did this bus thing where we parked everybody down in Marin County in various parking lots and bussed them up the mountain," recalled Mel Lawrence, the festival's co-producer, who would later serve as operations manager at Woodstock. Barry Melton of Country Joe and the Fish remembered the scene differently: "There were school buses going up and down the mountainside. There's nothing like driving down the center line on a motorcycle with a bus going one way and a bus going the other way and a foot of clearance on either side." Members of the Hells Angels, reprising their peaceful role at the Human Be-In in Golden Gate Park the previous January, helped find lost children and ferried musicians up and down the mountain road.

The lineup read like a cross-section of American popular music in mid-1967. Saturday featured the Charlatans, the Doors, Canned Heat, the Jim Kweskin Jug Band, and the Chocolate Watchband. Sunday brought Jefferson Airplane, the Byrds, Tim Buckley, Captain Beefheart and the Magic Band, the Steve Miller Blues Band, and the Sons of Champlin. Stanley Mouse, already gaining acclaim for his poster art for Bill Graham's Fillmore Auditorium and the Grateful Dead, designed one of the event's posters. To some commentators, the festival marked the moment when the Bay Area's hippie culture fully emerged and the split between "adult" and "teen" musical tastes became irreversible -- though pioneer rock editor Greg Shaw later argued that rift did not solidify until freeform radio took hold in the fall of 1967.

Contemporary press accounts noted something remarkable about the Fantasy Fair: there were no fights, no disturbances, and at the end of each day, the crowd placed their trash in or next to the garbage cans and left Mount Tamalpais as they had found it. The festival represented an ideal that later, larger gatherings would struggle to replicate. It was music as community building, staged on a mountainside amphitheater surrounded by redwoods and coastal fog, with a two-dollar ticket funding childcare for one of San Francisco's most underserved neighborhoods. The Summer of Love was about to explode across the national consciousness, but on that June weekend in Marin County, it began with school buses, borrowed motorcycles, and a mountain full of people who cleaned up after themselves.