Practice in second language learning can be broadly defined as ‘Specific activities in the second language, engaged in systematically, deliberately, with the goal of developing knowledge of and skills in the second language’ (DeKeyser 2007: 1). For the purposes of this book, these activities will be defined as mainly receptive (helping learners to process form-meaning links from the input) or mainly productive (helping learners to make form-meaning links from output). In other studies (e.g., Shintani, Li and Ellis 2013) this distinction has been termed Comprehension Based Instruction (CBI) and Output Based Instruction (OBI).This is, in some senses, a convenient division, as many forms of language practice will contain elements of reception and production. However, it is also a division which we feel many teachers will recognise – as different practice activities and methodologies often place greater emphasis on either understanding or use.