This paper investigates the role of social capital in influencing individuals' willingness to contribute to environmental protection in Sweden. Four indices of social capital comprising social trust, institutional trust, civic participation and a composite index comprising all considered elements of social capital were constructed to analyse their respective association with individual decisions to contribute. Using data from the environment module of the 2010 International Social Survey Programme, we empirically show that all four social capital parameters are significant and robust drivers of Swedish public's willingness to contribute when the payment vehicles are increased higher prices or taxes or through lifestyle changes to protect the environment. Statistically, a significant association was observed for social trust and civic participation. Institutional trust is not significant when the payment vehicle is a reduction in the standard of living. Overall, however, the composite index of social capital is a robust predictor of likelihood to contribute irrespective of the payment vehicle.