Résumé : The analysis of group dynamics has become a major challenge to capture parameters of collective work such as conflict, performance or team member satisfaction. To date, many interaction coding systems have been developed to help identify types of interactions among group members, but some shortcomings involving their structure, complexity and reliability remain. In this paper, we present the INSIDE TEAMS3D (IT3D), a new coding system dedicated to the study of verbal interactions in small groups and developed iteratively from varied group experiences. Its creation focuses on some significant requirements such as the user-friendliness of the system, the exhaustiveness of its categories, and the multidimensional essence of interactions. Thus, the IT3D takes account of three dimensions of individual behaviours which are the functional meaning of interactions, the convergence among interactions and the interpersonal emotional meaning of interactions. It hence provides a bigger picture on different aspects of group dynamics. Intercoder reliability and validity are also ascertained. Such a tool contributes to opening up new research and practical opportunities to a greater understanding of intragroup phenomena.