Abstract Why were stone projectile point blade margins serrated in some circumstances and not others? Carefully controlled experiments reported here are used to quantify the effects of this attribute on projectile performance. This research suggests that serration does not substantially alter point performance, and this characteristic may therefore vary independently of function. These results in conjunction with patterning in archeological data suggest that point blade traits including serration served as active symbols of sociocultural group membership in some areas, such as the Phoenix Basin in Southern Arizona.