This study focuses on the use of the native language (L1) by second language (L2) learners when carrying out a collaborative jigsaw task in a computer chat environment. It investigates the extent and function of L1 use by means of a sociocultural theoretical framework. The research project was carried out in three languages: Chinese, German, and Spanish. Students were assigned to dyads at random and were asked to perform a jigsaw task activity. The chat logs were collected and analyzed via descriptive statistics and discourse analysis. The findings suggest that across all three languages, the students used their L1 (English) to varying degrees and for a variety of functions. "Moving the task along" (Swain & Lapkin, 2000a) was the primary function of the L1. Further examination of the chat logs indicates that several factors affected the use of L1, such as participants' task management strategies and the use of symbols.