A distinctive feature of 21st-century constitution making is the role assigned to citizens through various forms of direct participation, as well as special efforts to include groups underrepresented and marginalized in ordinary politics. The legitimacy of these processes increasingly requires a role for actors and groups previously excluded from crucial institutional decisions (Elster 1998; Fishkin 2011; Reuchamps and Welp 2023; Rubio-Marin 2020; Welp and Soto 2020). However, vested interests have proven challenging to overcome amid a global crisis of representation. The failed Chilean process of 2021-2022 provides valuable lessons about the triumphs and pitfalls of embracing an open approach to constitution making.