The past decades have seen an explosion of research using electrophysiological or neuroimaging techniques for studying the neurocognitive underpinnings of second language (L2) processing. Although this field has a shorter history than does research on language learning more generally, important insights into the neurocognitive basis of L2 processing have driven it to the center stage of language science. In this target article for "Language Learning's" 75th Jubilee volume, I illustrate the field's impressive achievements by selectively reviewing electrophysiological and neuroimaging research on L2 processing and bilingual brain organization. I also review changing perspectives in the field (including individual difference and experience-based perspectives, neural network approaches, neuroplasticity, and L2-learning related neural changes) and identified challenges, promises, and future directions (revisit native-speaker benchmark, increase linguistic diversity, enhance ecological validity, intensify research on child L2 learners' brain, adopt lifelong approach to L2 learning) that can lead to a better understanding of the neural underpinnings of L2 learning and processing.