Explicit knowledge about language in L2 learning

<jats:p>This chapter discusses explicit knowledge about language in second language (L2) learning from a usage-based perspective, which is here defined broadly to include theoretical approaches such as complexity theory, emergentism, cognitive linguistics and related constructionist theories of language. A definition of explicit and implicit knowledge and learning is provided, followed by a brief outline of the main claims of the theories included under the usage-based umbrella. Then ways of measuring explicit knowledge in L2 learning that are compatible with a usage-based perspective are presented. Drawing on the theoretical concepts introduced as well as empirical findings to date, the role of explicit knowledge in L2 learning including both benefits and limitations is detailed. Finally, suggestions for further research are put forward.</jats:p>