Abstract: This talk illustrates how linguistic research can contribute to language learning by uncovering certain types of “invisible” linguistic structure that must be internalized in both first and second language acquisition.  Taking Japanese as a case study, three kinds of such invisible linguistic structure will be discussed:  the pattern of nouns that must be seen to occur with different  types of verbs, even if not visible on the surface (”argument structure”); the structure formed by the interplay between known and unknown information (”information structure”); and vertical structures formed by smaller units combining to form larger units (”constituent structure”).  Biography: Prof. Jacobsen was born and raised in Japan, returning to the U.S. in his later high school years.  After graduating from Wheaton College (Illinois) with undergraduate degrees in mathematics and religious studies, he did graduate work in linguistics at the University of Chicago, concentrating in Japanese linguistics and earning a Ph.D. in 1981.  Following graduate school, he taught Japanese language and linguistics for 12 years at the University of Minnesota before joining the faculty at Harvard, where he serves as Director of the Japanese Language Program.  He has spent research leaves in Japan at the National Language Research Institute in Tokyo, Kobe University, Dokkyo University, International Christian University, Kyoto University, and Osaka University researching concepts of time, reality, and event structure (especially transitivity) and their interaction in Japanese grammar and on the development of effective teaching strategies for such concepts.  His publications include The transitive structure of events in Japanese (Kurioso, 1992), Nihongo kyooiku no atarashii chihei o hiraku [Opening new horizons in Japanese pedagogy] (Hitsuji Shoboo, 2014, co-editor), Transitivity and valency alternations:  studies on Japanese and beyond (De Gruyter Mouton, 2016, co-editor).