The aim of the present study was to examine the social behaviour and competence of children, ages 3-6 as they progressed through the stages of second language acquisition in a dual-immersion program in English and Mandarin. Over 100 2-3 hour classroom observations were made during the school year. Teachers' evaluations of children's social competence and behaviour were collected at the beginning and end of the school year. Results suggest that girls had more social adjustment difficulties than boys. However, as language skills increased, adjustment difficulties decreased significantly among all children. (Contains 1 note and 5 tables.)