This paper conducts a comparative analysis of social capital and environmental management in two rapidly growing regions in south-east Asia, Bangkok and Ho Chi Minh City. Theoretical and empirical triangulation are used to clarify the nature of social capital and the ways that gender, in particular, affects trust and co-operation. Theoretical triangulation is accomplished by drawing on conceptual arguments made in economics, geography and urban planning to develop a theoretical framework explaining social capital and environmental management in south-east Asia. Empirical triangulation is accomplished through a multimethod analytical approach, including survey methods and experimental games conducted with the same populations. The results of the comparative analysis among squatter residents in Bangkok and Ho Chi Minh City are presented with a focus on gender differences in trust and co-operation and the paper concludes with a summary of the results and recommendations for policy and future research.