Researchers have identified social presence as one of several important areas in the study of computer mediated communication (CMC): "An analysis of social presence must be an important part of educators' efforts to understand how computer conferences function in educational settings, and how they can be made to function more effectively" (Garrison and Anderson, 2003)When visiting any classroom it does not take long to identify the presence or otherwise, of a "climate for learning". A skilful teacher will be able to maintain a balance between too much and too little social interaction between pupils, so that learning can take place. Careful management of the teaching situation can frequently achieve this. In contrast, e-learning can be a very isolated experience for many students. For example, online continuing professional development (CPD) courses being offered in many universities, result in a reduction of face to face tutorial support. Ensuring a climate for learning is frequently dependent upon an electronic discussion forum, which maintains contact and provides opportunities to exchange views with other students. However, if an online conference is to operate as an effective "learning community", then an appropriate level of social presence also needs to be there. This paper is part of a large-scale project in progress concerned with the analysis of a number of dynamic and diverse e- communities (Cook and Ralston 2002) focusing on identifying situations in which knowledge construction takes place (Ralston, 2003). A recently devised conceptual framework (Archer et.al, 2001) identified three key elements of an e-community to be cognitive presence, social presence and teaching presence. This paper, using this framework, looks in detail at one of these- social presence, and investigates its importance in supporting collaborative learning. Examples are used as illustrations from several recent e-conferences, including e-environments created for the Learning Schools Programme, part of a UK wide programme in developing ICT competence and confidence among teachers in which some 50,000 teachers participated. Key words: -Computer mediated communication, knowledge construction, social presence, learning community References Archer, W., Garrison, D. R., Anderson, T., & Rourke, L. (2001). A Framework for Analyzing Critical Thinking in Computer Conferences. Paper presented at EURO-CSCL 2001, Maastricht. Cook, D., Ralston,J.L.(2002) Sharpening the focus-Methodological issues in analysing online conferences. Paper presented to the European Conference on Educational Research, Lisbon (September 2002)Garrison, D R, Anderson, T (2003) E-learning in the 21st Century: A framework for research and practice RoutledgeFalmer Ralston, J.L (2003) E-Learning communities- knowledge creation in online conferences - some lessons learnt. Paper presented at the 4th International Conference on Information Communication Technologies in Education, 2003, Samos, Greece