Extreme heat is a critical global concern impacting human health, environmental sustainability, and equity in cities. Understanding which organizations are working on this issue and how they interact is fundamental to building urban heat resilience. To understand the flow of information among organizations working on extreme heat and the nature and strength of partnerships between organizations, we performed a social network analysis of organizations focused on heat in Los Angeles County. A total of 49 organizations were included in the study, representing non-profit organizations, governmental organizations, and educational institutions. We found that, topically, organizations in the region are involved in outdoor infrastructure through investing in urban greening initiatives, cool streets, and shade interventions. The network of organizations engaged in heat resilience activities is highly centralized – a handful of organizations hold the majority of influence regarding extreme heat. A large number of organizations are only weakly connected to the network. In addition to revealing influential organizations engaged in heat resilience activities in Los Angeles County, our analysis provides insights into how organizations relate to one another. While centralized networks hold some advantages such as quick dissemination of information, these networks can impede collaboration and limit overall progress in urban resilience.