Since the mid-1980s, demand-side management has been an important element of the electric utility planning approach referred to as integrated resource planning. At that time, annual demand-side management expenditures in the United States were measured in billions of dollars, energy savings were measured in billions of kWh, and peak load reductions were stated in thousands of MW. While activities nationally slowed during the couple of decades that followed the 1980s, activity has again been on the rise since the turn of the millennium. Expenditures for utility and third-party administered electric efficiency programs were nearly $6 billion in 2012, up from a low of $0.9 billion in 1998; in addition, estimated electric savings nationwide exceeded 22 billion kWh in 2011 (Hayes et al. 2013). Therefore, demand-side management practices have continued to persevere and have recently regained a considerable and growing influence on the demand for energy resources. This chapter defines demand-side management, describes the role demand-side management plays in integrated resource planning, discusses the main elements of demand-side management programs, and summarizes the key best practices for program design and delivery. It then presents case studies of four successful demand-side management programs.