Forms of violence vary greatly depending on level and scale considered: interpersonal, collective, intergroup, interstate. Their level of intensity, organization and institutionalization varies to such an extent that it might sometimes be difficult to see any commonality. What has domestic violence in common with war or genocide? To this heterogeneity of the object ‘violence’, one has to add the contested nature of the concept ‘violence’: widely divergent definitions of ‘violence’ inform academic debates on violent crime, domestic violence or political violence. Given this diversity of the objects and concepts of violence, it would be relatively vain to search for a general theory of violence in sociology. Just think of aggressivity (as a human faculty or individual tendency). You will surely recognize that it might play a part in some violent crimes and might even shed light on the comparatively higher propensity for violence of young males in comparison to young females in most societies. However, it hardly explains why two world wars happened in the first half of the 20th century, and none in the second half. Accordingly, most sociological studies try to account for diversity, singularity and heterogeneity rather than aiming for overarching explanations. This may be one of the hallmarks of sociological approaches to violence (Walby, 2013): they generally focus on one type of violent behaviour or consider multiple forms of violence in order to highlight specificities and differences. However, even so, authors and books focusing on forms of violence are rare in sociology. Reflections on violence and war tend to be dispersed throughout the literature with few authors connecting the different threads (Joas and Knöbl, 2012; Maleševic´, 2010). It is worth noticing that, traditionally, sociology has focused on criminal and interpersonal interactions when dealing with violence (Rule, 1989), leaving other types of violence to other disciplines. It is only with the rise of historical sociology in the 1980s, especially in the US, that sociologists have reclaimed war as an object of study rather than leaving it to political scientists as previously often was the case.