- Transitioning from fossil fuels to renewable energy sources has been identified by governments throughout the world as a key strategy for reducing air pollution and greenhouse gas emissions, enhancing sustainability and resiliency, and supporting local economies. Despite these benefits, this transition has been slow in the United States, causing some to rethink the current centralized electricity system. Applying the multi-level perspective (MLP) theoretical framework, this research assesses the spread of localities exploring Community Choice Aggregation (CCA) in California. These programs, which allow communities to choose their source of electricity supply through a locally-controlled public agency, have developed in California, challenging the current regime as part of a potential socio-technical transition. An analysis of how actors within localities have explored the implementation of CCAs is conducted through twenty four interviews with stakeholders and public officials, and a review of media and public documents within two California counties and their incorporated cities – Sonoma and San Diego. The findings demonstrate how macro-level pressures on the socio-technical regime created opportunities for niche policies to be framed as solutions, and provide evidence of how CCA advocates relied on early adopters to demonstrate viability and gained traction through network building and learning opportunities. The study also reveals implications of niches disrupting a socio-technical regime, including additional risks incurred, uncertainties created in the existing system, and the innovation’s ability to deliver on stated goals. Policy implications regarding stakeholder engagement, early policy adopters, and statewide coordination are also discussed.