Purpose: Wiki technologies, which are popular in social settings, are beginning to contribute to more flexible and participatory approaches to the exploitation of knowledge in corporate settings. Through the lens of activity theory, this paper aims to investigate contentious challenges to organizational activities that may be associated with the introduction of corporate wikis, in particular the potential democratization of knowledge work. Design/methodology/approach: From a study of several cases of corporate wiki adoption, this paper presents and interprets two representative cases sampled to provide more generalized results. Qualitative data were collected through semi-structured interviews and observation. The analysis followed a systematic process of data reduction, display, and rich interpretation using the concepts of activity theory. Findings: This research provides new understandings of the undervalued activities of knowledge workers, their challenges as wiki users and resulting implications for organizational transformation and improved organizational performance. Research limitations/implications: There is potential bias and limited scope as the choice of cases was determined through organizations known to the researchers and involved some action research. However, the authors justify this approach for a dynamic, emergent topic worthy of immediate investigation and direct applicability of findings to corporate practice. Social implications: This paper addresses the implications of new Web 2.0 technologies for the democratization of knowledge management in the workplace. Originality/value: The novelty of this work lies in using activity theory to explore reasons why some organizations are more successful than others in implementing wikis. This work contributes to research on how social and technological interventions may lead to improved exploitation of knowledge as a corporate resource.