Despite the crucial role of teachers in connecting research to classroom practices, very little is known about the processes of research-informed practice through their reading, doing, and use of research. Also largely unknown is how the potential interconnections among these activities could influence teachers’ evaluations of research relevance and sustainability of their research-informed practice. This study, therefore, explores trajectories of teachers in adopting research-informed practice. Relying on an ecological theoretical lens through a narrative case study approach, we collected data from three in-service EFL teachers using in-depth individual interviews, multiple follow-ups, teacher-generated research logs, and researcher-made analytic memos. Data analysis revealed specific starting conditions (e.g., subject-matter explorations) for development of rudimentary familiarity, turning moments (e.g., developmental thresholds) giving rise to more sophisticated reception, and bottlenecks (e.g., disciplinary identity) for sustained involvement in research-informed-practice for teachers. Furthermore, on top of cyclical links among reading, doing, and use of research, we found perceived signature patterns of reading (i.e., empirical papers), doing (i.e., action research), or use (i.e., successful classroom application) for each teacher, as evidence for threshold crossing. Implications for theory and research, professional development, and policymaking, including key prerequisites that must be provisioned to prepare teachers for research-informed practice, are discussed.