This paper examines the relationship between social capital and public sector performance in Thailand. Findings from an original survey of thirty provinces in Thailand indicate that a social networks, a core component of social capital, tends to increase the effectiveness of public goods particularly when accountability of public sector is weak. Provincial and local authorities do not tend to improve public goods and services a great deal as government resources increase. In Thailand, where the accountability of public sector is often weak, social capital therefore can improve public sector accountability and performance.