With some of the hottest summers and highest solar penetration rates in the nation, APS faces a uniquely and increasingly acute demand response challenge. As a part of a comprehensive demand response (DR) plan to meet this challenge, APS has partnered with Opower to provide behavioral energy efficiency (BEE) and behavioral demand response (BDR) programs to over 500,000 of its residential customers. These customers are producing verifiable energy and DR savings in the peakiest portions of the year on the APS grid; and are generating energy savings throughout the rest of the year as well. In order to accurately assess the success of each of the BEE and BDR programs, each of APS’ behavior-based programs has been designed around the gold standard of measurement—the randomized control trial (RCT). Each of the RCT waves at APS gives us a view on the ability of homeowner education and behavioral nudging to create a power grid that is at once more sustainable and stable. With accurate measurement, future program planning becomes more straightforward as reliable and verifiable reductions can be forecast with confidence. This working session will include three primary portions: 1) an overview of the treatment experience of each of the behavioral programs that APS is delivering to its residential customers, including their key differences and the goals of each type of behavioral intervention, 2) a review of the measurement methods applicable to each type of behavioral program and how the challenges of accurate measurement and attribution for overlapping programs can be overcome with high confidence and, 3) a review of the results of APS’ behavioral interventions to date, how they fit in with APS’ broader 400MW demand-side management portfolio, and an outlook to future peak season planning.