How does communication mode affect people's experience of social presence, presence, and performance, and how does it affect their actual collaboration in a virtual environment? In a first experiment, subjects communicated by text-chat, audio conference, or video conference in a desktop collaborative virtual environment (CVE). Both perceived social presence and presence were shown to be lower in the text-chat condition than in the audio- and video-conference conditions. People spent a longer time performing a decision-making task together, spoke fewer words in total, and also spoke fewer words per second in the text-chat environment. Finally, more words per second were spoken in the audio-conference than in the video-conference condition. In a second experiment, collaboration in a CVE audio- and a CVE video condition was compared to collaboration in a Web audio-conference and a Web video-conference condition. Results showed that presence was rated higher in the two video than in the two audio conditions and especially in the Web video condition. People spent more time in the video than in the audio conditions and more words per second were spoken in the Web than in the CVE conditions. In conclusion, it was found that both the communication media used and the environment in which collaboration takes place (CVE or Web) make a difference for how subjects experience interaction and for their communication behavior.