As most research on educational computer-mediated communication (CMC) interaction has focused on the asynchronous mode, less is known about the impact of the synchronous CMC mode on online learning processes. This chapter presents a qualitative case study of a distant course exemplifying the innovative instructional application of online synchronous (chat) interaction in virtual tutorials. While chat interaction has primarily been researched for its effectiveness in supporting social-emotional aspects of learning, this chapter reports survey findings on its impact on facilitating participation in collaborative group learning processes and enhancing understanding of course content from a sociocultural constructivist perspective. The results reveal factors that affected both student perception and use of participation opportunities in chat tutorials, and understanding of course content. The findings present implications for the pedagogical design of online synchronous collaborative-constructivist learning activities that enhance understanding of course content through dialogic participation in the learning process.