Thousands of settlements stippled the third millennium B.C. landscape of Pakistan and northwest India. These communities maintained an extensive exchange network that spanned West and South Asia. They shared remarkably consistent symbolic and ideological systems despite a vast territory, including an undeciphered script, standardized weights, measures, sanitation and subsistence systems, and settlement planning. The city of Harappa (3300-1300B.C.) sits at the center of this Indus River Valley Civilization. The relatively large skeletal collection from Harappa offers an opportunity to examine biocultural aspects of urban life and its decline in South Asian prehistory. This paper compares evidence for cranial trauma among burial populations at Harappa through time to assess the hypothesis that Indus state formation occurred as a peaceful heterarchy. The prevalence and patterning of cranial injuries, combined with striking differences in mortuary treatment and demography among the three burial areas indicate interpersonal violence in Harappan society was structured along lines of gender and community membership. The results support a relationship at Harappa among urbanization, access to resources, social differentiation, and risk of interpersonal violence. Further, the results contradict the dehumanizing, unrealistic myth of the Indus Civilization as an exceptionally peaceful prehistoric urban civilization.