On 21 May 1975 a chartered bus carrying 51 members of a student choir rolled from a sharply curved freeway off-ramp and fell 22 feet, landing on its roof, which collapsed. Twenty-nine passengers died (25 before extrication) and 22, plus the driver, survived. An analysis of factors leading up to the accident reveals several contributing causes, among them inadequate design of the ramp, poor warning signs, driver inexperience with the bus, and deficient bus maintenance. Bus design itself contributed to the lethality of the event. Structural support for the roof was inadequate and no access was available to the interior for extrication of victims. Problems with organization at the scene, triage, and communications among agencies involved in the rescue and receiving hospitals contributed to confusion in the transport of victims, although it appears this had little impact on outcome. An analysis of the accident allows several lessons to be learned which might prevent, or reduce, the fatalities from future accidents involving multipassenger vehicles, and other disasters with 10 to 25, or more than 25 fatalities. In the present report ten of 25 killed were judged possibly salvageable with immediate extrication.