Renewable portfolio standards (RPSs) and mandates to invest in cost-effective energy efficiency (EE) are increasingly popular policy tools to combat climate change and dependence on fossil fuels. These supply-side and demand-side policies, however, are often uncoordinated. Using California as a case in point, this paper demonstrates that states could improve resource allocation if these two policies were coordinated by incorporating renewable-energy procurement cost into the cost-effectiveness determination for EE investment. In particular, if renewable energy is relatively expensive when compared to conventional energy, increasing the RPS target raises the cost-effective level of EE investment. (C) 2008 Elsevier Ltd. All rights reserved.