We report the results of a trust survey and public goods experiment conducted with high school students in rural Thailand and Cambodia that together help clarify the dynamics at work in sustaining economic cooperation within these two third-world communities. We find that standard survey measures of trust employed by the World Values Survey, which form the basis of most macro-empirical investigations of trust and political-economic development, are not useful for predicting contributions to a public goods game. Expectations, on the other hand, profoundly influence contributions and do so independently of trust levels. However, this influence is complex and depends on the distribution of player types. We observe a distribution similar to previous studies, with the largest group, principled reciprocators, updating their behavior quickly based on expectations of trustworthiness. Indeed, this study suggests that trustworthiness in particular is more important than trust in general and further challenges ‘a-rational’ theories of trust.