Transitioning a large city such as Los Angeles to 100% carbon-free electricity requires collaboration among multiple actors with different and sometimes conflicting objectives. In this Cell Reports Sustainability article, Arent and colleagues describe a pioneering multi-scenario, multi-objective decision support effort, identifying specific pathways for Los Angeles to achieve its carbon-free goals that satisfy both day-to-day and transformational requirements. Here, we describe these pathways and the innovative, collaborative process that produced them.