Driving transformation takes a multifaceted, long-term approach. This session describes successful programmatic approaches to drive change across residential markets in the American Northwest, based on 15 years of research and evaluation studies. The program, the Northwest Energy Efficiency Alliance’s (NEEA) Northwest Ductless Heat Pump Project (NWDHPP), intervened in the residential HVAC markets of Idaho, Montana, Oregon, and Washington between 2008 and 2020. The NWDHPP drove adoption of DHPs (also known as ductless mini-splits) in site-built and manufactured single-family homes through engagement with manufacturers, distributors, HVAC contractors, and to a limited extent, consumers. By the end of the program’s direct interventions in 2020, NEEA had trained more than 1,200 HVAC contractors and more than 100,000 DHPs had been installed in homes. Ongoing evaluation studies show market transformation persisting into 2022, despite the pandemic, inflation, and supply chain disruptions. This presentation will highlight lessons learned and changes to the program’s approach over time, including its gradual shift from the traditional Market Transformation/Diffusion of Innovation Theory focus on “Early Adopters” of new technologies (typically middle-class, highly educated individuals living in urban areas) to an increased focus on accelerating adoption in manufactured homes and changing the behaviors of HVAC contractors in rural areas. In conclusion, the presentation will note remaining challenges to Market Transformation in the Northwest, as well as to more inclusive program and evaluation design.