The ability to encode, store and retrieve linguistic information long-term is key to effective second language learning and use. Alongside its importance for second language acquisition theory, investigating the role of long-term memory is fundamental to advance pedagogical implementations, in the effort to optimise language instruction and maximise its effectiveness by catering for individual learners’ differences. In order to achieve these goals, the role of variability in explicit and implicit long-term memory has been investigated employing methodology developed in neuropsychological research in laboratory settings. More recently, this research programme has extended to less controlled, but also more ecologically-valid, instructed contexts, included in the foreign language classroom. This article aims at reviewing these studies, as well as at providing an overview of recent research advancing new proposals on how the findings of long-term memory research can be implemented to benefit L2 pedagogy.