Social factors play an important role in determining whether instructional communication in computer-supported settings will be successful. "Social presence" is a social factor, specifically addressing the feeling of being present with another person in a virtual environment. This article describes possibilities to influence the feeling of social presence in synchronous learning scenarios using desktop collaborative virtual environments (CVEs). Desktop CVEs are technically simple compared with immersive CVEs and can be adapted according to the needs of the users. In this article, possible adaptations are described using the example of the desktop CVE virtual team room. In CVEs, users are represented as avatars. Avatars may or may not convey nonverbal signals. The focus of the article is on whether the actual use of nonverbal signals can affect the sense of social presence and thus help to establish and maintain the learner's motivation and provide support for structuring social interaction in learning situations. The paper provides a review of exploratory studies and experiments as well as a report on the author's own studies. Future research questions concerning learning in CVEs are discussed.