Vygotsky's zone of proximal development (ZPD) has been fruitfully applied in L2 research that examines second and foreign language learning. This paper considers the applicability of the ZPD to interlanguage pragmatics instruction and research. First, the ZPD is defined [Vygotsky, L.S., 1978. Mind in Society: The Development of Higher Psychological Processes. Harvard University Press, Cambridge, MA], and definitions are queried in light of differences between second language learning/development from the child development context for which the ZPD was developed [Ohta, A.S., 2001a. Second Language Acquisition Processes in the Classroom: Learning Japanese. Lawrence Erlbaum Associates, Mahwah, NJ; Ohta, A.S. The zone of proximal development and second language acquisition: Beyond social interaction. In N. Negishi, T. Umino, A. Yoshitomi, (Eds.), Readings in Second Language Acquisition and Second Language Pedagogy in a Japanese Context. John Benjamins, Amsterdam, in press]. Then, three interlanguage pragmatics research studies involving instructional intervention are considered through the framework the ZPD provides. These are [Takahashi, S., 2001. The role of input enhancement in developing pragmatic competence. In: Rose, K.R., Kasper, G. (Eds.), Pragmatics in Language Teaching. Cambridge University Press, Cambridge, pp. 171-199.], a study of explicit/implicit instruction of English biclausal requests; [Samuda, V., 2001. Guiding relationships between form and meaning during task performance: The role of the teacher. In: Bygate, M., Skehan, P., Swain, M. (Eds.), Researching Pedagogic Tasks: Second Language Learning, Teaching and Testing. Longman, New York, pp. 119-140.], a study of the impact of teacher intervention on task-based instruction in English modals; and [Yoshimi, D.R., 2001. Explicit instruction and JFL learner's use of interactional discourse markers. In: Rose, K.R., Kasper, G. (Eds.), Pragmatics in Language Teaching. Cambridge University Press, Cambridge, pp. 223-244.], which examines the impact of instruction on Japanese conversational storytelling. Analysis suggests how the zone of proximal development impacted the development observed in the three studies and how instructional methods tested did nor did not tap into the potential of the ZPD. The paper concludes with recommendations for researchers and teachers, suggesting how the notion of the ZPD can be used both to better understand pragmatic development and to improve instruction in L2 pragmatics. (Contains 4 tables.)