In the Kumingan district of Jakarta, a giant pair of brazed steel-made sixes looms between high-rise buildings. The ‘66,’ in gleaming metal implying progress and modernity, is a monument for mass murder. It celebrates those who declared themselves the ‘generation of 1966’ in that year – university students and other youth who helped bring down the Sukarno regime, the ‘old order’, and did so by participating in ‘crushing’ the political left and murdering at least 500,000 people in 1965–66.

Young urbanites were just one of the groups that teamed up for these killings. This chapter revolves around mass participation in violence and examines in which ways it is based on multiple motives – both are important characteristics of an extremely violent society which led to a diverse coalition for violence in Indonesia. The nature of this coalition is used to explain why violence was so tempestuous, why it spread against groups other than leftists (another feature of an extremely violent society), but also why violence took different forms and intensities and where it had its limits. This question is important because most leftists survived. Moreover, the chapter explores in which organizational frameworks activities by non-state actors took place, how actions by political groups or mobs were related to forceful government policies of persecution, and how the political polarization among citizens was linked to longer-term social change. In this way, it attempts to integrate the political and social history of mass violence.