Executive Functions (EFs) include cognitive processes such as attention, problem solving, inhibition, cognitive flexibility and working memory. EFs develop throughout childhood and into early adulthood, and are essential for school readiness and success. The significant role of EFs in academic achievement and beyond brings to light the distinct disadvantage of children who experience EF deficits. Deaf children, like some other groups with atypical development, have been found to have delays in EF development, particularly in planning, problem solving, and inhibition. This thesis reports the findings from two studies investigating EF in two groups of deaf participants. The first study explores the EF skills of a unique group – deaf musicians. This study compares the EF skills of deaf and hearing adult musicians with deaf and hearing non-musicians. The results reveal similarities in the EF profiles of deaf and hearing musicians, adding to the current debate in the literature about the impact of musicianship on EF skills and the underlying mechanisms that drive gains in EF through music. The second study, which is the main focus of the thesis, describes a musicbased EF intervention carried out with deaf children in three London mainstream primary schools. It covers the design and implementation of the intervention, what effect the intervention had on children’s EF (in particular, the significant impact found on children’s working memory and inhibition skills), the implications of the findings for existing models of EF, and the potential for using musical training to improve deaf children’s EF skills. Results from both studies indicate that music-based EF training may be a valuable tool for improving EF skills in deaf individuals and highlights the need for further investigation into the relationship between music and EF within the deaf population.