This article explains how research “on” practitioners can be turned into research “for and with” practitioners (Cameron, Frazer, Rampton, & Richardson, 1992, p. 22) by including these practitioners in the research teams. Methodologically, it draws on two decades of multimethod research and knowledge transformation at the interface of Applied Linguistics and transdisciplinary action research on professional communication (Perrin, 2013). Empirically, it is based on large corpora of data collected in multilingual and multicultural workplaces. First, the article outlines transdisciplinary action research as a theoretical framework that enables researchers and practitioners to collaboratively develop sustainable solutions to real-world problems in which language use in general and text production in particular play a substantial role (Section 1). Then, Progression Analysis is explained as a multimethod approach to investigate text production practices in natural environments such as workplaces (Section 2). Examples from four domains (education, finance, translation, and journalism) illustrate what value transdisciplinary collaboration between academic researchers and practitioners can add to knowledge generation in Applied Linguistics (Section 3). For the case of journalism in increasingly global contexts, in-depth analyses offer step-by-step understanding of the trajectory from a real-world problem to a sustainable solution (Section 4). The article concludes by suggesting empirically-based measures for research that contribute to the development of both theory and practice in Applied Linguistics (Section 5).