This historical-theoretical article reviews prewar efforts at a “Marx-Freud synthesis,” stressing the rejection among socialist psychoanalysts of Freud's death-instinct theory. It then considers a second form of synthesis that was developed after World War II: a practical synthesis focused on meeting the needs of children and families traumatized during the War that would work through social democratic state programs and services in which psychoanalytic research on child development would be key. But psychoanalytic contributions were less influential as postwar theorists explored both the origins of war and the nature of prejudices—a topic that once again became crucial as European social democracies were challenged in the 1980s with internal inequality, strife, and prejudice against immigrants. The article raises questions about what currently needs to be done theoretically both to continue the postwar exploration of developmental needs and to extend work on prejudices.