Homeownership is considered an essential part of the \American Dream" and forms the foundation of upward mobility. We show that the upward mobility of children from low-income families is not predicted by homeownership rates, but by homeownership segregation. Higher residential segregation between homeowners and renters predicts lower upward mobility of children from low-income families, while not affecting high-income families. We hypothesize the 1968 Fair Housing Act preserved homeownership segregation in CZs since the 1970s, and feature more land-use regulation even today. Channels mediating the effect of homeownership on upward mobility include income segregation, racial segregation, school segregation, and commuting times.