These neighborhoods—which we call America’s most diverse, mixed-income neighborhoods—have high levels of racial, ethnic and income diversity. This report identifies, maps and counts the nation’s most diverse mixed-income neighborhoods. In these neighborhoods, residents are much more likely than the average American to have neighbors from different racial/ethnic groups than themselves, and neighbors with different levels of income. We find that: Nearly 7 million Americans live in neighborhoods with both high levels of racial/ethnic and economic diversity; Roughly half of these neighborhoods are found in three of the nation’s largest, most diverse metropolitan areas: New York, Los Angeles and San Francisco; Most large metropolitan areas have several neighborhoods that are among the nation’s most diverse and mixed income; Forty-four of the nation’s 52 largest metro areas have at least one diverse, mixed-income neighborhood; The racial and ethnic diversity of a metropolitan area sets the context for having diverse, mixed income neighborhoods; Whether metropolitan diversity is reflected in the lived experience in the typical neighborhood depends on how segregated a metropolitan area is by race, ethnicity and class; Some metropolitan areas come much closer to realizing their potential for neighborhood racial/ethnic diversity, given their metropolitan demographic composition.