Rupture of the ground surface by faulting associated with shallow earthquakes is an important element to consider in the evaluation of fault activity. Observational data compiled in this report indicate that the minimum earthquake magnitude associa ted with reported sudden surface faulting is about M, 5. Considering that the epicentral areas of many earthquakes of M, 5 or less were not searched for evidence of surface faulting, the actual minimum magnitude may be smaller. A combined empirical and theoretical analysis suggests that under ideal c onditions, coseismic surface faulting of a few millimeters associated with earthquakes having moment magnitudes as small as 3 could be recognized by simple field methods. Several factors such as dimensions, depth, and orientation of the rupture surface together with observational conditions affect the development and subsequent recognition of surface faulting. Surface displacements ranging from a few millimeters to several decimeters have accompanied earthquakes having magnitudes between 5 and 6. The larger fault displacements and the earthquakes can damage structures, and that possibility should be considered in regions where shallow earthquakes of that size can occur. The generally small and short surface ruptures associated with such earthquakes may leave very little evidence in the topogra phy, stratigraphy, or near -surface structure, especially if the displacements are consistently small and the recurrence intervals for earthquakes are long. Such c onditions may explain why so few active faults have been recognized in some regions of infrequent shallow eart hquakes, such as eastern North America.