This Issue Paper offers a brief overview of the crime of migrant smuggling. It explains aspects of the crime as defined in the Protocol against the Smuggling of Migrants by Land, Sea and Air (Smuggling of Migrants Protocol) supplementing the United Nations Convention against Transnational Organized Crime. The paper also explores how the crime of migrant smuggling is committed, the roles played by individual criminal actors in the process, and explains the difference between migrant smuggling and the distinct but related crime of human trafficking.