This article examines the sustainability of externally promoted participatory budgeting (PB) over more than a decade and, given the results, considers the implications for participatory practice in international development. In 2009, I investigated the continued utilization of PB as introduced through a US-financed local government development project in post-war El Salvador. I examined all 28 project municipalities 5 years after the project ended and found limited but important PB sustainability. In 2015, I replicated the study, using the same parameters in the same 28 municipalities, more than 10 years after completion of the project. This article presents the findings of the latter study and compares them with 2009 results. PB continues to be utilized in more than half of the 28 municipalities examined-a striking example of long-term sustainability -although there is also little continuity of use among individual municipal governments. I conclude that PB is becoming institutionalized, in part because of the initial project. This case of sustainability and institutionalization of PB may allow us to be more optimistic about the potential effects of participation in international development. Copyright (C) 2017 John Wiley & Sons, Ltd.