This chapter firstly outlines the phonological structure of Gaelic and aspects of phonetic implementation. I then consider methods used so far in the study of Gaelic phonological acquisition and review work in this area. The journey of language acquisition is varied across different sectors of the Gaelic-speaking population, as well as individuals. For example, while some children acquire Gaelic and English virtually simultaneously in the home, other children acquire Gaelic sequentially through a form of immersion schooling known as Gaelic Medium Education (GME). Many lie somewhere on a simultaneous-sequential continuum. Adult acquirers of Gaelic are a hugely diverse population, which naturally leads to a range of differing outcomes in the acquisition of phonology. In this overview of the field, I consider the different factors associated with multilingual phonological acquisition, and how they have predicted or challenged results obtained from data-driven studies of Gaelic. The chapter ends with a discussion about the multiple future directions needed for research in this area, including larger studies of primary-aged populations, and more focus on universities as an important locus of adult language acquisition.