Virtual environments systems based on immersive projection technologies (IPTs) offer users the possibility of collaborating intuitively in a 3D environment. While considerable work has been done to examine interaction in desktop-based collaborative virtual environments (CVEs), there are currently no studies for collaborative interaction using IPTs. The aim of this paper is to examine how immersive technologies support interaction and to compare this to the experience with desktop systems. A study of collaboration is presented where two partners worked together using networked IPT environments. The data collected included observations, analysis of video and audio recordings, questionnaires and debriefing interviews from both IPT sites. This paper focuses on the successes and failures in collaboration through detailed examination of particular incidents during the interaction. We compare these successes and failures with the findings of a study by Hindmarsh, Fraser, Heath, & Benford (Computer Supported Collaborative Work, CSCW'98, 1998, pp. 217–226) that examined object-focused interaction on a desktop-based CVE system. Our findings identify situations where interaction is better supported with the IPT system than the desktop system, and situations where interaction is not as well supported. We also present examples of how social interaction is critical to seamless collaboration.