Well-determined fault plane solution and the gross pattern of late-Cenozoic faulting in California and Nevada show a systematic relation between the orientation of fault planes and slip directions. In general, normal faults have N strikes, reverse faults have E strikes, and dextral and sinstral strike slip faults have NW and NE strikes, respectively. Kinematically, this relation is consistent with the response of clusters of fault-bounded crustal blocks to a regional stress field generated by the relative motion between the Pacific and N American plates. In this stress field, the greatest and least principal (compressive) stresses are restricted to N and E striking vertical planes, respectively. Simple arrangements of block clusters mimic the gross kinematic pattern of Quaternary faulting in California and Nevada. Some implications for contemporary tectonics emphasized by this model involve the W displacement of the Sierra Nevada block with respect to the stable interior of the N American plates, oblique thrusting of the Salinian block over the Pacific plate, and a progressive increase in the offset of the San Andreas fault represented by the 'big bend' through the Transverse Ranges. -from Author