Purpose - The purpose of this paper is to investigate the role played by value systems as mechanisms for organizational change. Three issues are examined: purpose; implementation; and effects, intended and unintended, that may arise from using values systems as a management control mechanism to effect organizational change. Design/methodology/approach - The research is based on evidenced garnered from an in-depth, longitudinal study of a major UK based organization which operates in the "global communications industry". Data are collected from a range of sources, but particularly interviews and a questionnaire survey involving a broad cross-section of the company's managers. Findings - Findings suggest that, in terms of purpose, top management may use value systems as a management control mechanism to effect organizational change by espousing a new set of normative values which should inform managers' decisions and actions, particularly in trade-off situations. Communication and implementation of value systems may involve a multitude of formal and informal information-based mechanisms and procedures, including mission statements, newsletters, email, "strategy days", "roadshows" and similar social events. Implementation may rely on change agents creating a drive for change. However, the results of a questionnaire survey suggest that value systems may be only partly successful in securing their intended purpose of mobilising attitudes around a particular set of normative values. Various unintended effects may arise which, in the present case, include increasing project redundancy, decreasing project scrutiny, a re-distribution of social esteem within the firm, polarisation of attitudes towards budgetary control, and a general reduction in the exercise of hierarchical management control. Overall, it argued that the use of value systems as a mechanism of organizational change may be as problematic to the firm as it is beneficial. Practical implications - The results of the present study may help firms devise more appropriate value systems for "maintaining or altering patterns of organizational behaviour". Originality/value - The present study contributes further insight is through evidence which suggests value systems may be used to communicate a set of quite specific values; and adds to a knowledge of the range of procedures which may be involved in using value systems to effect organizational change.