Not just mixed use, mixed income

Why mixed-income neighborhoods matter: Lifting kids out of poverty

An important part of building a robust neighborhood is not just putting in mixed uses that encourage destinations that are close enough to walk to, but also striving to create housing choices so that residents with a mix of income levels can live there as well. Developments where all the housing was built at the same time in a similar style tend to have housing that is affordable and appealing to people in similar income brackets. By contrast, neighborhoods that provide a diversity of housing options, building at different times, are more accessible to people at different income levels.

This article in Strong Towns discusses some recent research on the benefits of mixed income neighborhoods.

Poor kids who grow up in more mixed income neighborhoods have better lifetime economic results. This signals that an important strategy for addressing poverty is building cities where mixed income neighborhoods are the norm, rather than the exception. And this strategy can be implemented in a number of ways—not just by relocating the poor to better neighborhoods, but by actively promoting greater income integration in the neighborhoods, mostly in cities, that have higher than average poverty rates.
— Joe Cortright, Strong Towns