Published online by Cambridge University Press: 09 November 2015
In low-income countries, grassroots collective action for the management of a common environmental resource is a well-known substitute for government provision of public goods. In our research we test experimentally what its effect is on social capital. To this purpose we structure a ‘sandwich’ experiment in which participants play a common pool resource game (CPRG) between two trust games in a Nairobi slum where social capital is scarce but informal rules regulating the commons are abundant. Our findings show that the change in trustworthiness between the two trust game rounds generated by the CPRG experience is crucially affected by the subjective satisfaction about the CPRG, rather than by standard objective measures related to CPRG players' behaviour. These results highlight that subjective satisfaction in a collective action has relevant predictive power on social capital creation, providing information which can be crucial to designing successful self-organized environmental resource regimes.