The United Nations Protocol Against the Smuggling of Migrants by Land, Sea and Air sets out an ambitious international approach to prevent and combat the smuggling of migrants. Although the Protocol has found widespread adoption worldwide, many countries have not—or not yet—signed and ratified the Protocol. Many critics argue that the Protocol promotes the views of rich, developed destination countries and offers little incentives for developing countries of origin to support the Protocol. This paper examines the reasons why some countries choose not to ratify the Protocol. The paper sheds light on the common concerns and characteristics of the forty-five non-Party States in order to pave the way for wider adoption of the Protocol and for more concerted efforts to combat the smuggling of migrants worldwide.