Implicit learning is the learning of underlying regularities hidden in the environment without the learner being conscious of what is being learnt. First language acquisition in young children is essentially implicit (Krashen, 1982), but the role of implicit learning in second language acquisition is debatable. Previous research on learning of tonal languages focused on perception and identification of language tones in relatively explicit settings, and showed that tonal language experience may not help with learning a new tonal language in an explicit setting (So & Best, 2010; Wang, 2006). Yet, little research was done on the implicit learning of language tones, and on whether prior tonal language experience plays a role in such implicit learning. In this study, simplified Thai tonal rules were used as a learning target to investigate if implicit learning of such rules is possible. Implicit learning performance among native tonal language speakers with no knowledge of Thai, non?tonal language native speakers who have learnt/have been learning tonal languages other than Thai, and non?tonal language speakers with little knowledge of tonal languages were compared. Results showed that the native tonal language group implicitly learnt the target, and some trends of learning were found in the tonal language learner group, but not in the tonal language na?ve group. This advantage of tonal language experience over the learning of tonal patterns suggested that tonal language experience can be transferable to the learning of a new tonal language in implicit settings. This suggested that, rather than being hindered by their prior linguistic experience, learners with some tonal language background may benefit from implicit settings when learning a new tonal language. / published_or_final_version / English / Master / Master of Philosophy