Most research examining the relationship between social capital and outcomes focuses on either internal social capital or external social capital. This article examines the impact of both internal and external social capital on the success of self-organizing community initiatives. A study of community water projects in a developing country, Nepal, shows that communities that enjoy less internal conflict and more external partnerships are more likely to be successful in securing agency funds for their projects. Also, communities face trade-offs between internal and external social capital. These dimensions of social capital are not perfect substitutes, and communities that maintain a strategic balance between the two maximize gains from a trade-off. Moreover, such an optimal choice is dependent on the level of internal and external social capital that these communities hold.