Aims: This article reviews recent research on the relationship between language and thinking in bilinguals.
Approach: The paper reviews aspects of previous research, and links it to the articles in this special issue.
Conclusions: Research on language and cognition in bilinguals requires both depth (in-depth investigations of one area in order to test approaches and methods) and breadth (investigations of a wide range of research areas). It should cover all levels of language and all aspects of cognition, in line with the latest theoretical and methodological developments in relevant disciplines (e.g. using linguistic and non-linguistic tasks, collecting quantitative and qualitative data).
Originality and significance: This introduction discusses important theoretical and methodological aspects of recent developments in the field.