Information Technology is no longer regarded solely as a repository within knowledge management but also as a collaborative tool. This change of role gives rise to online communities (OLCs), which extend the loci of existing communities of practice. To leverage the potential of these communities, organisations must understand the mechanisms underpinning members' decisions to share knowledge and expertise within the community. This paper discusses existing research and develops a theoretical model of factors that affect knowledge sharing in OLCs. The aim is to increase our understanding of the antecedents to knowledge-sharing in OLCs.