Bilingualism is now widely considered to be akin to cognitively challenging experiences that cause structural adaptations to the brain. However, the available research has so far yielded variable patterns, including effects showing both increases and reductions in grey matter volume and white matter diffusivity as an effect of bilingualism. This presentation reviews the available evidence and compares it to patterns from other domains of skill acquisition, culminating in the Dynamic Restructuring Model, a theory which synthesises the available evidence from the perspective of experience-based neuroplasticity.