This chapter is devoted to an exploration of human trafficking, a phenomenon that has existed for centuries. While all sexes and gender identities are at risk of being trafficked, women and girls are markedly over-represented. This chapter addresses the history of trafficking of women, and universally accepted definitions of trafficking, treaties and laws prohibiting trafficking, with a focus on the increased risk and vulnerability of women and girls being trafficked, specifically sex trafficking. Vulnerability to trafficking cannot be understood from one dimension; rather, the interface of an individual’s characteristics and personal history within a complex and dynamic system of external factors has to be considered. This multilayered system consists of the immediate social situations and relationships of an individual, coupled with their environments and the national patterns of economics, policy decisions, and cultural forces that impact their local community. All of these aspects are further influenced by globalization and transnational policies. Case studies illuminate how the intersection of various vulnerabilities can heighten the risk of women to be trafficked, specifically addressing those that are seeking asylum in the United States and their remarkable resiliency.