While Lombroso presently enjoys a certain notoriety, there exists very little serious social historical analysis of his highly influential theories of crime. Positivist criminology had important ramifications within post-unification Italian politics generally — and even within late nineteenth century socialism. It has been suggested elsewhere that in Italy of the 1860s, Darwinism encompassed but quickly moved beyond the relatively weak tradition of physical science and was rapidly applied to the fields of history and politics. To pose the putative dialectic between criminal and society, organism and environment, still begged the question of the origin of the microbe which then found the broth. The chapter describes the coherence and credibility of Lombroso's work in late nineteenth century Italy: the ways in which his research responded to, and was constrained by, the political concerns and pressures of that time and place. For classical theory ideal placed the onus on proving the terms for exclusion from the polity.