This article focuses on mobility as a crucial aspect of prostitution and human trafficking. I distinguish between horizontal (geographical) and vertical (organizational) mobility to analyze the context in which women, their families, agents, and other actors decide to move from one place to another in the framework of sex-work activities. Data used in this article derive from the ongoing research on human trafficking and prostitution in western and eastern Europe. This research is carried out through participant observation among migrant prostitutes and through interviews and content analysis of media reports in several countries.