Although the distinction between explicit and implicit (automatized) knowledge of second or foreign language (L2) is of crucial importance to second language acquisition (SLA) theory and research, it has thus far not been directly applied to L2 pronunciation. The paper attempts to fill this gap by making an initial attempt to illustrate the relevance of this vital distinction in this area. Following the discussion of some crucial preliminary issues, the two types of knowledge are characterized and challenges involved in their measurement are considered. Subsequently, the distinction is related to theoretical accounts of how L2 pronunciation is learnt and empirical investigations into the effectiveness of different types of pronunciation instruction as well as everyday instructional classroom practices. The role of mediating factors, such as individual differences or contextual influences, is also considered.