Complete Streets are designed to accommodate safe travel for all modes and all users. In essence, the idea is that this public space should embrace diversity. Yet, decades of policy experimentation in fostering and maintaining diversity-for instance, in public schools or mixed-income housing-have shown that it is always more challenging than anticipated. What is diversity? A population that perfectly represents the universe or an equal mix of different groups defined by ethnicity or class? And in the specific case of urban design, given the impossibility of envisioning all potential users, how can designers keep diversity in mind when planning a public space?