In Australian two-way immersion programs approximately 20-40% of instruction takes place in the target language. While much has been written about such programs targeting French and German, little has been written about Japanese immersion programs. The aim of this research is to provide a better understanding of children's second language development in partial immersion programs in the Australian context. The following questions are addressed in this study: What is the nature of young children's discourse in immersion classes? and When, for what purposes, and what types of second language (L2) utterances do young children produce in immersion classrooms? Naturalistic data were collected from science classes from lower grade levels. Young children's L2 utterances are first examined quantitatively and are further analyzed qualitatively in relation to interaction with their teachers and peers. Twenty-four children, ages five through seven participated in this study. It is found that most of the children's utterances were formulaic expressions or one- or two-word statements. (Contains 21 references.) (KFT)