This chapter addresses the concept of slavery, exploring its character and significance as a dark page in history, but also as a specifically criminological and zemiological problem, in the context of international law and human rights. By tracing the ambiguities of slavery in international law and international development, the harms associated with slavery are considered. Harms include both those statutorily proscribed, and those that are not, but that can still be regarded as socially destructive. Traditionally, antislavery has been considered within the parameters of abolition and criminalization. In this context recently, anti-trafficking has emerged as a key issue in contemporary anti-slavery work. While valuable, anti-trafficking is shown to have significant limitations. It advances criminalization and stigmatization of the most vulnerable and further perpetuates harm. At the same time, it identifies structural conditions like poverty, vulnerability, and “unfreedom” of movement only to put them aside. Linked to exploitation, violence and zemia, the chapter brings to the fore some crucial questions concerning the prospects of systemic theory in the investigation of slavery, that highlight the root causes of slavery, primarily poverty and inequality. Therefore, the chapter counterposes an alternative approach in which the orienting target is not abolition of slavery but advancing structural changes against social harm.