The North American electric power grid is a large existing distributed network that will present new stability and control problems should the penetration of distributed renewable sources, controllable loads, and local-area energy storage capabilities become a significant portion of the overall grid. Roof-top solar panels and small wind turbines represent renewable sources, plug-in hybrids or all electric vehicles represent controllable loads, and battery packs would be local storage devices. Although the current affordability of traditional energy sources and the slow sales pace of electric and hybrid vehicles have slowed this penetration to the point where classical methods appear adequate for the near future, it makes sense to consider power grids of the future where sources may be located in the power distribution network rather than the transmission network. This talk introduces a control-theoretic framework for studying voltage stability and its robustness, as well as optimal power management in distribution systems. It represents work done in collaboration with a group of researchers at Wayne State University.