How do rural communities make important decisions about farming techniques? What determines, for example, whether neighbouring households share information and decide to adopt a new technology or not? ‘Social assessments’ can enhance understanding of such social processes; but at a cost of around US$100,000, are they worth it? At Middlebury College in the United States, analysis of household data from Tanzania suggests that the positive effect of social capital on fertiliser adoption makes a strong case for using social assessments to improve the probability that agricultural households will adopt new technologies.