Six-year-old Antoni, born in the UK to Polish parents, speaks only a few English words in class and often looks confused when the teacher gives instructions. He could simply be adjusting to English – or the problem could be developmental language disorder (DLD), a condition that severely impairs a child’s ability to learn, use and understand spoken language. Such challenges are increasingly common for parents and teachers. In England, for example, around 21% of schoolchildren are growing up with a first language other than English. While most children’s language development – whether monolingual or multilingual – is typical, the average classroom includes two DLD-affected children. DLD’s prevalence, roughly 8%, is similar worldwide, from China to Mexico. Even so, DLD remains under-recognised and under-served – especially compared to other developmental conditions, such as dyslexia, autism or attention deficit hyperactivity disorder (ADHD). Identifying DLD in multilingual children can be difficult. Each language a child learns develops at its own pace, depending on factors such as how often they hear and use it. For example, multilingual children may …