To fully understand the source of long-term effects of bilingualism and/or to explore how to potentially leverage language learning for healthy aging, it is essential to first unpack adult language learning itself. The early stages of adult novel language learning offer a unique window into the neurocognitive processes involved at the very onset of learning. In this talk, Megan Nakamura will discuss findings from a study that investigates the neurocognitive mechanisms underlying adult language learning in the early stages––after only 5-7 hours––and the modulating effects of prior bilingual experience and executive functions, namely, inhibitory control and verbal working memory. We used a pre/post shortterm longitudinal design wherein participants underwent a 10-day Dutch language training intervention using Rosetta Stone®. To track neurophysiological changes associated with learning, we used EEG to record Event-Related Potentials (ERPs) during a Semantic Categorization Task (SCT) designed to measure the lexicalization of new words from pre- to post-test. Our results showed significant reductions in N400 amplitude at post-test for learned words, indicating successful semantic integration and rapid neural adaptation. These findings replicate and extend the results of McLaughlin et al. (2004) and Bakker et al. (2015). Notably, we found that this N400 attenuation was modulated by individual differences in prior bilingual experience, inhibitory control capabilities, as well as cognate status of words. These insights highlight the interplay between the characteristics of novel words, existing language experience, and cognitive control mechanisms during the early stages of novel language learning.