While the corporate lingua franca mandate aims to facilitate communications among linguistically diverse employees, evidence shows that it creates more problems than it solves, often negatively affecting social integration and knowledge sharing in the workplace. Our study is driven by the phenomenon of high language diversity and low lingua franca proficiency, emerging characteristics of workplaces around the globe given increasing migration. We adopt a mixed-methods, longitudinal design involving participant observations, interviews, social network surveys, and company data. Our analysis revealed the existence and prevalence of an informal language advice network (LAN) in which individuals with varying levels of English proficiency actively engage in voluntary language-related knowledge-seeking and sharing. We found more positive interpersonal interactions and consequences of LAN than typically reported in extant studies. We leverage the social networks and generalized exchange literature to explain the processes and consequences of LAN for individuals and the organization. Management recognition was found to be important for sustaining LAN in a context of high language diversity. Our integrative analytical framework offers a valuable lens for scholarship on future workplaces that are being shaped by rapidly shifting ethnic, cultural, and linguistic demography.