Abstract The Pfeiffer case is illustrative of how geologic facts, events, and terminology can be central to the outcome of a controversy between an insured party and his insurance company. Gravity sliding occurred which damaged the dwelling of the insured. Geological testimony was used to determine causes; the possibility of recurrence; and the advisability of rebuilding at the site. In addition, such testimony was judicious on whether there was negligence on the part of the builder or the insurance company because they did not realize the geologic conditions would lead to large-scale gravity sliding. Geologic facts revealed that causes were visible and the landslide was foreseeable; therefore it could not be passed over by the insurance company as "an act of God#. The Pfeiffer case involved a decision concerning landslide insurance and the payment of damage to the insured. The court decision, which has since been precedent for other cases, was based on the critical geologic conditions and events that affected the site of the insured dwelling. The sole issue was "Does an insurance policy which insures a dwelling against the perils of landslide, include the foundation underlying the house, as well as the house structure itself?" Interestingly, this crucial point had not been clarified by a court decision prior to the Pfeiffer case. Insurance companies had customarily accepted no responsibility for the subsurface foundation part of the dwelling, arid awarded damages for repair of the building only. The Pfeiffer's were awarded $31,000 in a judgment of August I960 for repair of their dwelling to the conditions of the house and foundation prior to the landslide damage. Other important precedents in landslide insurance coverage concerned with geologic conditions are reviewed in this paper; all cases were decided uniformly in favor of homeowners on all major issues. The Pfeiffer dwelling is situated on the slope of a northwest trending ridge of the Berkeley Hills at Orinda, California. Everywhere the area is underlain by rocks of the Orinda Formation which consist of alternating beds of siltstone, soft, fine-grained sandstone and conglomerate, clay shale and clays. At the site, the natural slope is 20° to 40°; the underlying rock sequence dips up to 45° and more or less parallel to the surface. A mantle of soil and colluvium up to 10-feet thick overlies the soft, fractured and saturated Orinda beds. Gravity sliding, as determined by both surface and subsurface investigations, was caused by a series of geologic events, both ancient and current, which combined to create the slide of April 1958 that damaged Pfeiffer's dwelling. The numerous internal causes are described; no major external causes, such as earthquakes, were responsible.