Computer-mediated communication (CMC) technologies are increasingly being used to support collaborative learning in groups. Its potential to shift the traditional pedagogical paradigm triggers considerable amount of research. However, very few of the research studies focus on the social interactions and their influences on the learning process, which are crucial to understanding computer-supported collaborative learning (CSCL). This paper reports on a laboratory experiment with a 2×2 factorial design, conducted to investigate the influences of cultural diversity and leadership availability on the CSCL process using a content analysis approach. With the mediation of CMC systems, cultural diversity is found to engender more informational influences but reduce normative influences. Leadership has a positive effect on both normative and informational influences. Taking into account the learning outcomes, it is evident that the influences of the interaction process are closely related to CSCL effectiveness.