Based on about one hundred criminal cases which were tried by a Court of Appeal in the southwest of the Paris region over ten years (1987-1996), this article presents the demographic and social characteristics of 122 murderers and their victims. It brings out the very high proportion of individuals from the working classes or from the poorest strata of the population among the population of murderers as well as of victims, and the weight of economic inactivity and unemployment. The importance of family disruption (desertion, various types of foster care) and still more importantly, of family conflicts, is emphasized. On an empirical level, these findings are compared with those of studies conducted in other countries, particularly the abundant quantitative literature from North America. On a theoretical level, this article takes its place among discussions initiated by American authors who have worked on the notions of disorganization and social disintegration, and by French authors who have worked on the notions of disaffiliation, disqualification and dis-insertion, and who suggest that researchers move beyond the mere social and family characteristics of the individuals at the time of the crime and take into account their life histories and particularly the family and school elements that left their marks on their entire life itinerary.