As we work to provide coherent and systematic professional development for online language teachers, a consideration of findings from teacher development research is essential. This essay begins by briefly overviewing this research as well as investigations into teacher learning related to online instruction, with a specific focus on studies grounded in sociocultural theory (Lantolf, 2000, "Sociocultural theory and second language learning," Oxford University Press, Oxford, England; Vygotsky, 1986, "Thought and language," MIT Press, Cambridge, MA). The main takeaways from this study are exemplified through the teacher professional development efforts currently underway at the Center for Advanced Research on Language Acquisition at the University of Minnesota. The essay concludes with recommendations for crafting a research-informed professional development program for online language instruction.