This article adopts a mobilization framework to examine the crucial actions of workplace activists in overcoming fear of employer reprisal during union organizing campaigns in hostile environments. The article explores fear as part of the organizing process in two ways; first, we examine how fear can act as a stimulus for workplace activists to take action in an attempt to overcome the source of that fear. Second, we examine fear as an inhibiting factor in organizing, whereby the presence of fear hinders individuals from taking action. Using qualitative data from interviews conducted with workplace activists across a variety of campaigns in Ireland, this article examines the process through which workplace activists conquer their own sense of fear and undertake the task of mobilizing colleagues toward collective action in pursuit of union representation amid fear of employer reprisal.