Regions across the United States have developed sustainability plans and programs funded through the U.S. Department of Housing and Urban Development’s Sustainable Communities Initiative (SCI). In California, this grant overlapped with a state mandate for regional sustainability planning, SB 375, legislation charging regions with developing long-range sustainability plans to reduce greenhouse gas emissions. Regional agencies lead sustainability planning efforts, yet little is known about how effective and equitable regions are in their engagement with sustainability planning. We examined how three federally funded SCI projects in California incorporate social equity and explore the process and outcomes. We focus on the conditions under which regional collaboration is most conducive to incorporating equity. We found that equity approaches vary greatly by region and are as much about process as product. Networks of information sharing, trust and relationships in regions awarded SCI grants have increased. However, regional sustainability planning processes are not without conflict as participants maneuver though historic institutional challenges.