This study explores the role of emotion in political mobilization by studying People Power, a radical group in Hong Kong. The group abandoned their disruptive approach and adopted a new tactic of social movement—joyous resistance—which attracted large numbers of participants and thus became a powerful political force exerting great pressure on the government. This case shows that festive emotion can be an intangible resource that reduces the cost of participation compared with confrontational tactics. The cathartic function of joyous resistance also reduces the potential for violence during mobilization. After the Umbrella Movement, there has been debate on whether more confrontational or even violent tactics should be adopted in social movements. The idea of joyous resistance will remain an important option for social movement organizers considering the sustainability of mobilization in a moderate society such as Hong Kong.