Language processing is a product of the human brain. In this respect, language acquisition and language development should also be considered in the context of brain functional and brain structural changes during child development. Using electrophysiological and functional imaging methods, the brain bases of specific processes can be observed directly and compared depending on age and language development status. This direct access provides a significant opportunity to gain a deeper understanding of the processes underlying language development and to understand language as a neurocognitive function. At the same time, structural-anatomical aspects of brain development can be considered in connection with milestones in language acquisition, thus demonstrating the crucial building blocks and connections of the language network in the brain and its development. This chapter introduces important experimental methods as well as the neurocognitive foundations of language development, and explains their relevance by a number of important empirical findings. For related topics in language development, see Chapter 18 (this volume) on developmental language disorder and Chapter 17 (this volume) on individual differences in language acquisition.