Based on research in a border village in Northeast Thailand and two villages in Laos, this paper discusses how formal regulations on cross‐border migration are negotiated, such that the practice becomes socially acceptable amongst receiving communities. This paper focuses on the border‐crossing experiences of Lao migrants to argue that regulations governing the Thai–Lao borders have been circumvented in response to labour demands in the Thai borderlands and mutual interest between local state officials and borderlanders. It is illegal for undocumented migrants to cross the Mekong to work in the farms along the Northeast Thai–Lao borderlands, but the practice has become socially acceptable. This licit status helps Lao migrants to navigate local state authorities, who are also involved in local social relations.The importance of local social relations is emphasised by differences in cross border‐migration between jobs in agriculture and jobs in service industries. In urban settings, migrants do not participate in local social relations to the same extent. Consequently, they are viewed as illicit, as well as illegal. While acknowledging the ongoing legal constraints on migrants and their movements, this paper seeks to provide an understanding of how state authority in the border regions is mediated by enduring social relations that create a legitimate space for informal and mutually beneficial actions.