Belonging to groups is often based on shared features between members and is associated with higher levels of (social) well-being. One especially strong marker of one's group membership is language. In linguistics, most research about group membership and well-being focuses on migrants and refugees. However, very little research has focused on the link between speaking a regional language and well-being. This is surprising, as regional languages index a strong shared in-group identity that could lead to exclusion of those who do not speak them. As a first empirical step, this paper reports on the association between regional language use (specifically, of Frisian and Low Saxon) and social well-being. We distributed a language background questionnaire to participants of the Lifelines cohort, a multigenerational cohort study comprising data from 167,729 participants living in the north of the Netherlands. In both language contexts (Frisian in Fryslân, and Low Saxon in Groningen and Drenthe), those using the regional language half of the time or more were found to have significantly more social contacts. They also experienced higher levels of social embeddedness than those who did not know or did not frequently use the regional language. The higher degree of social embeddedness for frequent regional language users was most strongly present in rural areas. Furthermore, we found that frequent users of Frisian living in Fryslân had higher levels of social embeddedness in rural areas than frequent users of Low Saxon living in Groningen or Drenthe. No effect was found for more overt measures of social well-being such as loneliness or life satisfaction. While our results confirm an association between regional language speaking and some indices of social functioning on a large scale, they cannot uncover a causal relationship between the two. We discuss how longitudinal studies and interviews in future studies may inform us further about the relation between regional language use and social well-being.