Electric power systems need to ensure that production and demand of electricity are continuously in balance. With fundamental changes taking place in the power grids of many countries due to a variety of technological and policy developments, there is a need to obtain additional flexibility to achieve this essential power balance. Demand response refers to the collection of all the means to obtain this flexibility from the demand side of the balance. We present a selection of contributions of operations research to the provision of demand response by the residential, commercial and institutional sectors of the economy. The aspects covered include electricity tariffs, building energy management systems, load estimation, local generation, electric vehicles, energy storage, and building-level aggregation. We conclude with a brief discussion of current opportunities for operations research to support the development and realization of the potential of demand response.