Scipio Sighele (born June 24, 1868, in Brescia to October 21, 1913, in Florence) was an Italian psychologist, sociologist, criminologist and a pioneer of mass psychology. He studied law at the University of Rome and taught at the Free University of Brussels from 1892 to 1902. He is also famous for the work The Criminal Crowd.[1] In this work, he mentioned Enrico Ferri, a contemporary colleague and friend, for several times. They shared more or less the same view about the influence of a crowd on the members of that crowd. This fundamental idea was also described by Gabriel Tarde and Gustave le Bon. Scipio Sighele and Gabriel Tarde debated on how to determine and assign criminal responsibility within a crowd and hence who to arrest.[2]