Background: Employees are undertaking a vital role in challenging the organizational practices that are contributing to the issues in contemporary society. Prior research has noted the generational shift in workplaces as an increased share of Millennials are bringing their values of sustainability to work. Employees engaging in actions to generate social change, also known as employee activism, is assumed to have either adversary or advocacy impact for organizations. Yet, what factors affect Millennials in practicing employee activism for change towards sustainability has not been proposed, thus this research will help to understand the perspectives of employees to advance current knowledge.  Purpose: The purpose of this thesis is to explore Millennials’ engagement in employee activism that as a result contributes to a sustainability change in Swedish workplaces. Method: The research uses an interpretivist lens to inspect nine employees' experiences through semi-structured interviews. The research compliments as well as extends existing knowledge through an inductive approach. Conclusion: The findings indicate several enablers and/or inhibitors on three levels. Firstly on a personal level, based on an individual's personality and attitude. Secondly, in terms of interpersonal relationships, relations within the workplace was recognized as a factor. Thirdly, on an organizational level, the structure of a company and employment were also deemed as affecting significantly the activism behaviors. In addition, the findings also suggest a rising recognition of the concept among employees as well as the steps that led to improvements in organizational practices.