This qualitative research study explored levels of social presence in Second Life (virtual world) associated with phases of knowledge construction. The study explored images and data collected from users at two discussion-based activities. The findings revealed the three levels of social presence, according to the Interactional Process Model of Social Presence developed by Schultze and Brooks. Social presence established a sense of mutual monitoring of users that increased users' sense of presence. This made their virtual interactions more real. Various phases of knowledge construction were observed as specified in the Interaction Analysis Model developed by Gunawardena, Lowe and Anderson. Knowledge construction indicated users shared information and negotiated meaning together. The findings showed Second Life can support users' experiences of higher levels of social presence and knowledge construction. This association provides insights for designing curriculum in virtual worlds, implying that collaborative activities with perceived availability for social interaction may lead to higher levels of knowledge construction. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]