Haury (1943, 1950) has demonstrated that Hohokam was an outgrowth of a western and slightly differentiated branch of San Pedro Stage, as Mogollon developed out of the eastern branch. Certain similarities in ceramic and lithic complexes of Mogollon and Hohokam in the earliest phases of each leave little doubt that there were close relationships at that time. Nevertheless, there existed technological differences in the pottery, and other differences, which require explanations before we can judge the nature of the relationships and whether or not more than a single source for pottery is indicated.