The acquisition of Irish as a second language in a four-year-old child of bilingual parents attending an Irish-language preschool group in Ireland is chronicled, with emphasis on the characteristic features of her language learning process and the factors determining which language she uses with others. The study was based on transcribed adult-child conversations with a high proportion of question-answer interactions. The distinctive features discussed in detail include the use of the Irish vocative, colors and numbers, use of prepositions and constructions in which the subject is expressed by means of a preposition, sentence complexity, transfer of discourse skills, participation in conversation, and the productive use of questions as a learning strategy. (MSE)