Functional specialisation and plasticity are fundamental organising principles of the brain. Since the mid-1800s, certain cognitive functions have been known to be lateralised, but the provenance and flexibility of hemispheric specialisation remain open questions. Language is a uniquely human phenomenon that requires a delicate balance between neural specialisation and plasticity, and language learning offers the perfect window to study these principles in the human brain. In the current study, we conducted two separate functional MRI experiments with male and female language learners, one cross-sectional and one longitudinal, involving distinct populations and languages, and examined hemispheric lateralisation and learning-dependent plasticity of three language systems: reading, speech comprehension and verbal production. A multi-pronged analytic approach revealed a highly consistent pattern of results across the two experiments, showing that (i) in both native and non-native languages, while language pro...