In recent years, the flow of migrants and refugees through the Balkans has significantly increased. To date, there has been limited empirical evidence of when, why and how vulnerability to human trafficking arises in mass movements of migrants and refugees. New patterns of vulnerability and exploitation challenge established procedures for identification of and assistance to trafficking victims. This paper presents different experiences of trafficked migrants and refugees who have moved to and through Serbia over the past two years, and explores challenges and barriers to their formal identification and assistance as victims of human trafficking. The paper concludes with specific recommendations on how government and civil society stakeholders may begin to work more effectively on this issue to and to better identify and assist trafficked migrants/refugees.