While Chap. 1 was devoted to the discussion of key issues related to language learning strategies (LLS) as well as a synthesis of empirical research in this area, the present chapter zooms in more narrowly on grammar learning strategies (GLS), which are the focus of the research project reported later in this volume. The first section of the chapter, however, offers a brief overview of key issues related to the knowledge of second or foreign language (L2) grammar as well as the processes involved in learning and teaching this target language (TL) subsystem. This overview is indispensable to highlight the complexity of L2 grammar, which indicates that even seemingly the most propitious constellations of instructional options cannot ensure full mastery of this TL subsystem in the limited classroom time that teachers have at their disposal, certainly not in the case of all learners. While it might be challenging enough to help students understand relevant rules and use related grammar structures in controlled exercises, a particularly daunting challenge is ensuring that learners automatize this explicit knowledge to such a degree that they can effectively deploy the grammar features in spontaneous interactions under time pressure (DeKeyser, 2017; Ellis, 2009a; Pawlak, 2019c, 2021a, 2021c).