Public opinion is often treated as an obstacle to good governance in resource-rich developing countries, associated with populist policies and excess consumption. Can ordinary citizens in a low-income democracy make meaningful judgements about complex resource management issues? We report on a nationwide poll of voting-age adults in Tanzania, where large natural gas reserves were recently discovered. Results from a randomized experiment within our nationwide polling sample show that the combination of information and extended, structured, and participatory deliberation generated (i) a measurable increase in knowledge of the gas sector; (ii) increased support for sale of natural gas and reduced support for energy subsidies; (iii) no change in support for saving versus spending gas revenues; (iv) a sharp decline in support for direct cash distribution of resource rents to citizens; (v) increased support for spending on social services as opposed to infrastructure; and (vi) a marginally significant increase in support for transparency and oversight measures. Democratic deliberation appears to be the key to these changes; the information treatment alone produced no significant impacts, and impacts did not spill over onto individuals in the same community who did not participate in deliberation. As part of a second-order experiment to measure public accountability, we provided the citizens’ polling results to elites before polling them on a subset of the same questions. Our analysis indicates that elites demonstrate a tendency to align their views with public opinion on most major issues.