Executive control refers to a set of supervisory processes that enable humans to flexibly shape thoughts and behavior in order to accomplish internal goals. Normal human aging is associated with marked decline in executive control functions. However, recent evidence suggests that lifelong bilingualism may attenuate age-related declines of some executive control functions. These findings suggest that bilingualism may promote neuroplasticity and/or compensatory brain reserve. However, despite potentially large social and scientific implications, considerable knowledge gaps exist in this field. The present work will fill several of these gaps through a series of studies aimed to understand the influences of bilingualism on cognition and neurobiology in aging. Specific Aim 1 is to obtain more detailed information about the influence of lifelong bilingualism on high-level working memory processes. Specific Aims 2-4 use cutting-edge neuroimaging methods to understand the neurobiological bases of bilingual executive control advantages. These aims are to understand potential functional neuroanatomic (Aim 2), structural grey matter (Aim 3), and white matter microstructure (Aim 4) bases of bilingual performance advantages, by linking imaging patterns directly to behavioral performance. Specific Aim 5 is to determine which bilingual cognitive/neurobiological advantages correlate with degree of experience/practice with the second language. Given the projected increase in the aged population, it is important to understand how specific lifestyle factors may affect age-related cognitive and neurobiological declines. Results from the present proposal will provide a detailed description of how an accessible lifestyle variable can offset age- related cognitive declines through neurobiological plasticity and/or compensatory brain reserve. Finally, research relevant to understanding the consequences of bilingualism is an issue of fundamental importance in our increasingly multilingual society. PUBLIC HEALTH RELEVANCE: Normal human aging is associated with decline of executive control functions. Recent evidence suggests that bilingualism may attenuate some of these age-related declines by promoting neuroplasticity and/or compensatory brain reserve. By providing a more precise understanding of the mechanisms that are bolstered by bilingualism, the present proposal will help identify cognitive/neurobiological markers that remain malleable in aging in response to an accessible lifestyle variable.