Abstract This paper investigates the impact of decentralization reforms on cooperation and trust at the village level in Tanzania, using a gender perspective. The paper draws on survey and qualitative data from ten villages in two rural districts. The findings show that the reforms have revitalized 'formal’ cooperative efforts and social networks and groups aimed at improving public services and poverty reduction. Citizen’s participation in decision-making processes and users’ satisfaction with public services are significantly related to social and political trust, in which gender plays a role as well. There is a two-way interface between trust and decentralization reforms. ‘Good’ decentralization outcomes generate trust while ‘bad’ outcomes decrease trust.