[en] Informality is often linked to borderlands in both academic scholarship and political debates. On one hand, border regions are known for the flow of goods, services and labor and, of course, borders represent state attempts to control or regulate these flows. At the same time, scholars of border politics often discuss the weakness of state administrations in border regions where authorities are far from central governments. Despite the clear relevance of informal sectors for borderlands studies, there is a dearth of analysis of this topic in border areas, especially in comparative terms. This article presents a comparative cross-regional study of informality in European (the Eurométropole and Bari, Italy–Durres, Albania) and continental American (San-Diego, USA–Tijuana, Mexico and Cúcuta, Colombia–San Crístobal, Venezuela) cases. It responds to the following research questions: How can we compare informality in cross-border regions? How does informality relate to illegality in these regions? How can regional organizations respond to the social impacts of informality?