This article discusses the possibilities that tacit knowledge could provide for social constructivist pedagogies; in particular, pedagogies for online learning. Arguing that the tacit dimension of knowledge is critical for meaning making in situated learning practices and for a community of practice to function, the article considers whether individuals’ online identities can be employed as a way to reveal their tacit knowledge. Furthering the discussion, the article analyses tacit knowledge within a community and suggests that social capital theory could productively be employed for utilising tacit knowledge within any given online learning community.