A democratic workplace is one where workers as a body have the right to determine the internal organization and future direction of the firm. Worker co-operatives are a type of democratic firm. In a worker co-operative employees are joint-owners of the firm and participate democratically in workplace governance. Much has been written about the supposed benefits of worker co-operatives for workers and for society. One thread of this research, originating with Carole Pateman's theoretical work (Pateman 1970), argues that worker co-operatives act as sites of political learning for workers. By participating democratically in workplace decisions, individuals are thought to learn the skills and psychological dispositions needed to participate in political democracy. A second thread argues that co-operatives will improve worker well-being. Democratic governance will give workers control over work organization, increasing autonomy in their daily lives, and leading to an increase in non-material work rewards such as job satisfaction. Worker ownership will equalize the material rewards from work and improve job security.These arguments are premised on the idea that democratic governance structures and worker ownership will lead to widespread, effective worker participation in decision-making and the equalization of power at work. However, insufficient attention is given to the contextual factors beyond formal governance and ownership structures that shape the internal dynamics of workplace democracy. I conduct an in-depth, mixed-methods case study of a worker co-operative with 158 employees in the UK cycling retail industry. Using survey research, social network analysis, in-depth interviews and direct observation, I show how individual differences, firm-level contextual factors such as the social composition of the organization, and macro-level factors such as economic and cultural context, lead to unequal participation opportunities and different outcomes for different groups of workers within the firm.My research leads to three conclusions. First, the outcomes of workplace democracy for workers are highly context-dependent. They will differ across groups of workers within co-operatives, across different democratic firms, and across cultures. Second, the relationship between workplace democracy and political participation is more complex than the Pateman thesis suggests. It is contingent on the political identities of workers, which are themselves shaped by wider political economic context. Political identity affects both participation behaviour at work, and how workplace experience shapes political views. Third, the subjective well-being outcomes of workplace democracy depend on workers' expectations about work. Expectations are shaped by the same forces that mould political identity. Workplace democracy raises expectations for certain groups of workers, leading to well-being harms when expectations are not met. Overall, the benefits of workplace democracy for workers and for society are overstated. In the UK context, co-ops are unlikely to realize the benefits attributed to them without large-scale public policy interventions.