It has often been claimed in academic literature and the media that multi-unionism, or the presence of two or more recognised trade unions in a workplace, is problematic for both trade unions and management. The problems which arise, it is maintained, stem from inter-union rivalries, sectionalism and disputes over demarcation for example. The consequences are damaging, it follows, for union cohesion, for bargaining arrangements, and for changing work practices; thus innovation in how work is performed is obstructed. Drawing predominantly upon data from the UCD Survey of Employee Relations and Human Resource Practices, such claims are subject to scrutiny. Management perceptions of levels of conflict, the industrial relations climate and the introduction of workplace change and innovation are contrasted in both multiunion and one union workplaces. The findings cast some doubts over multi-unionism's reputation; little evidence is found which supports the notion either of a highly conflictual industrial relations climate, or that workplace change is significantly obstructed in such workplaces.