The chapter asks why household behavior matters for deep decarbonization, and how laws, policies, and programs that target behavior change can be employed to facilitate decarbonization. The pathways set forth in the DDPP reports all presume widespread public acceptance of new policies, as well as changes in household actions that directly affect carbon emissions, mainly via consumer adoption of technologies that have lower GHG footprints. While none of the DDPP pathways relies on explicit behavior change interventions to achieve emissions reductions, behavior change remains central to the project: the demand for energy services and uptake and use of technologies that reduce carbon emissions, particularly in the domains of energy efficiency and renewable energy, require massive amounts of behavior change between now and 2050. Because factors affecting individual and household behavior differ per behavioral type, interventions need to be tailored to specific behaviors. It is also important to recognize that public and private initiatives both play a role in driving the kinds of behavior change necessary to achieve deep decarbonization. The best available research indicates that achieving the rates of adoption included in the DDPP pathways is indeed feasible; however, this will require more than policies that require change or make adoption financially attractive. The most realistic analysis of the potential for change must consider the technical potential for change, the behavioral plasticity, and the policy plasticity (or feasibility) of adopting and implementing the best-known interventions.