We mainly study the initiation and management of small-scale irrigation facilities collective action in Northwest China. First, socio-economic heterogeneity imposes obstacles for initiating collective action in the form of attitude-behaviour paradox. We explore how to overcome this in order to make collective action successful. Social capital has been recognized as a key factor in the realisation of collective action. Then, we study the relationship between social capital components and farmers’ participative behaviour. Furthermore, economic heterogeneity would influence farmers’ motivation to participate in collective action. We examine whether relationships between social capital components and farmers’ willingness to cooperate in collective action is moderated by farmers’ income levels. Finally, we also study how contrasting effects of the group size exerts on trust and control mechanisms in achieving farmers’ participation degree and cooperative performance in commons governance.