A recent area of interest in machine learning involves drawing inferences from a large number of agents, each with some partial information. Such problems arise in a number of settings, with recent areas of interest including recommender systems and sensor networks. Problems in collective decision-making are also closely related to a fundamental problem of democracy — that of inferring the collective will of the people. This talk will give a brief overview of machine learning and voting theory, followed by a discussion of some of our recent work in these areas.