1 The proposed study aims to investigate the effects of music training on the development of executive function 2 skills (EF) in a population of school-age children, from under-resourced communities of Los Angeles. Executive 3 function (EF) refers to a number of core cognitive capacities that allows the coordination of thoughts, decision 4 making and planning. Development of these skills is increasingly recognized as an important contributor to 5 well-being throughout the life span. There is particular interest in EF skills in children, given the considerable 6 brain and cognitive developments associated with this period of life. Furthermore, low socio-economic status 7 on its own may affect negatively the course of EF development. On the other hand, children from these 8 disadvantaged communities have been shown to benefit the most from any intervention that has the potential 9 to improve EF. Playing music is a task that engages many different brain regions; it requires the concurrent 10 recruitment of distinct sensory and motor systems and their interplay with the attention and affective systems. 11 Learning to play a musical instrument requires mastering abilities related to EF such as auditory working 12 memory, motor inhibition and cognitive flexibility and has been suggested to benefit EF. Two groups will be 13 recruited to participate in the proposed study: the experimental group will be monolingual, native English- 14 speaking children, ages 9-11, from under-resourced communities of South and Central Los Angeles, who have 15 had 2 years of music training with YOLA, a community-based free music education program. The comparison 16 group will consist of children of the same age, from the same neighborhoods and socio-economic background, 17 also monolingual, who did not have any previous experience of music training. Electrophysiological (EEG), 18 neuroimaging (MRI) and behavioral probes will be used to assess the impact of music training on EF and its 19 neural underpinnings. The findings from this study will provide answers to the ongoing discussion about 20 music?s role in childhood education curricula, especially in underprivileged communities for whom access to 21 private or out of school music education is limited, or none. By focusing on these communities, our findings will 22 address a gap in the knowledge of child development and may serve to guide more effective public policies. 23 In addition, under separate funding, we are evaluating the effects of music training, also with YOLA, in a 24 bilingual child population from the same socio-economic background, using the same approach. We will 25 compare the results from the two studies. Like music training, bilingualism has also been shown to have 26 positive influence on EF development. However, it is not clear whether these two learning experiences 27 influence EF similarly, or through distinct mechanisms. Comparison of the results obtained here in monolingual 28 children with those obtained in the parallel bilingual group will allow the evaluation of the developmental effects 29 of these two learning experiences. It will also allow the understanding of the differences, or similarities, of 30 cognitive and brain development in children living in under-resourced urban communities. 1