In the international literature on assessment there seems to be common agreement that clear assessment criteria are necessary for an effective assessment strategy (Miller, 2003; Woolf, 2004). It has also been frequently observed in practice that the publication of explicit criteria is not suffi cient to promote effective student engagement in assessment. In this chapter we explore this problematic issue of explicit criteria and transparency of assessment from a socio-cultural perspective, using dialogism and Wenger’s concept of ‘communities of practice’ (1998).