In the smart grid, the power usage of households are recorded and analyzed in (near) real time by utility companies. The usage data enables a utility to manage its electric power supply to neighborhoods more efficiently and effectively. For instance, to prevent a power outage during a peak demand period, the utility can determine the power supply threshold for a neighborhood. When the total power usage of the neighborhood exceeds the threshold, certain households in the neighborhood are required to reduce their energy consumption. This type of power usage control benefits electric utilities and their consumers. However, the energy usage data collected by a utility can also be used to profile an individual’s daily activities – a potentially serious breach of personal privacy. To address the problem, this paper specifies distributed, privacy-preserving energy usage control protocols that enable utilities to efficiently manage power distribution while ensuring that individual power usage data is not revealed.