As the most serious crime, homicide is both relevant and suitable for cross-national comparisons. The global homicide rate of ca. 6 per 100,000 people is an average of hugely diverging national rates ranging from 0.25 in Singapore to ca. 100 in El Salvador. The validity of global homicide statistics suffers from various differences in definitions as well as reporting and registration processes. Both criminal justice and causes of death statistics are used by the World Health Organization to construct rates, yet these are available only for a minority of countries. An overview on homicide in history and non-state societies shows that violence levels were considerably higher compared to those in today’s developed world and have dropped dramatically in Europe and North America during the early modern period. The rates first increased and then declined between ca.1960 and today in most developed nations in a synchronized manner, hinting at common influences. In recent years, homicide trends have shown a polarizing pattern, with increasing rates in Latin America and decreasing rates in most other world regions, especially East Asia and the Pacific, where rates have fallen below the European average concurrent with rising scores on the Human Development Index. Except in Eastern Europe, the frequency of homicide is strongly linked to the use of firearms, which account for 44% of homicide cases worldwide.
Longitudinal studies have produced robust evidence for the pivotal role of deprivation and inequality in fostering lethal violence and of social welfare policies in reducing it. Although the transition to democratic political systems seems to increase homicide rates temporarily, the legitimacy of state institutions and the suppression of corruption are connected to lower homicide rates. Because of conceptual and methodological problems, questions concerning the generalizability of effects across space and time remain. Nevertheless, the research findings are sufficiently robust to draw important conclusions for violence prevention: reductions in poverty and income inequality, investments in welfare policies and gender equality, and improvements in the legitimacy of state institutions will help to bring homicide rates down.