An extremely rare handbill for The Grateful Dead, Country Joe & The Fish and the Mobius Band playing outside the walls of San Quentin Prison north of San Francisco. This was an event organized by The Diggers, the San Francisco radical community action group; the handbill was printed by the Communication Company, their communication wing. The Communication Company printed flyers and handbills from January-August, 1967, and this is a previously undocumented Dead gig (they also played outside San Quentin in March, 1968–but that was a Thursday, and long after the Communication Co. ceased printing.) Note this is a free show, urges people to "bring raw meat," and promises "colors, people, acid." This handbill comes from the archive of Ralph J. Gleason, longtime SF Chronicle music critic, co-founder of Rolling Stone Magazine, and prominent supporter of the San Francisco Scene. 8 1/2" x 11", in near mint condition. A historic and hitherto unknown Grateful Dead document.