This report provides a comprehensive portrait of California’s common interest developments (CIDs), which include planned developments, condominiums, and cooperatives. It focuses on planned developments, which now make up more than 40 percent of new single-family home sales and most resemble local governments in their scope of activities. It finds that, on average, their residents are older, more prosperous, and less racially and ethnically diverse than residents in comparable neighborhoods. However, planned developments do not seem to represent a “secession of the successful.” Income diversity in these communities is greater than might be expected, and voting patterns do not differ markedly from those of similar populations with different living arrangements. Although planned developments make only minor contributions to statewide metropolitan residential segregation, this pattern may change as CIDs account for more of the state’s total housing stock.