These concluding reflections seek to put the articles of this special issue in a broader context. The article begins by looking at the ideas of cognitive linguistics and linguistic relativity that are invoked. It then considers the questions that arise about the relationship between two or more languages in the same mind, the differences between the thinking of monolinguals and bilinguals, and whether cognitive changes in bilingualism are language-specific or universal and how they might contribute to language teaching. The aim is both to help the reader appreciate the nature of these contributions and to raise some, probably unanswerable, questions about this research domain. The intention is to bring out some of what this particular approach to second language (L2) research is, and is not, saying. The approach to second language acquisition (SLA) to which the contributions belong treats the second language (L2) user as a many-sided whole, in whom the languages interact with other mental systems, rather than as only the possessor of a grammar, concentrating on the complex relationship between language and cognition. The articles form part of a thriving SLA research movement, described in books such as Pavlenko (2011, 2014), De Groot (2011), and Cook & Bassetti (2011) that has started to explore how L2 users think--bilingual cognition--primarily through psycholinguistic experiments and techniques. They draw on the wing of cognitive linguistics that Evans (2011) calls "cognitive approaches to grammar" rather than on the "cognitive lexical semantics" wing, by focussing on how motion is expressed in speech, particularly on two key approaches to the relationship of motion and language, namely those by Talmy (1985) and Slobin (1996), who are referred to in all but two of the articles. The contributions to this special issue ask questions about L2 acquisition that would have been unthinkable 10 years ago and that allow SLA research for the first time to approach major issues about language in the human mind.