Sustainable food systems require mechanisms that assure consumers about the sustainability of agricultural production. Building on the existing literature on the impact of sustainability standards, this study is the first to assess the effectiveness of participatory guarantee systems (PGS) for the certification of organic produce. The study uses representative farm-level data on local vegetable value chains in northern Vietnam and uses a broad set of sustainability outcomes as well as counterfactual analysis, including systematic robustness checks. The results show that PGS significantly improves farm profitability (+117%), agroecology performance (+40%), and gives farmers more choice of sales channels (+23%). However, PGS had no significant effect on returns to labour and reduced the average crop yield. Capacity development on nursery practices, transplanting of healthy seedlings rather than direct seeding, reduced tillage, and collective crop planning and management are some of the innovations that can counter adverse effects on crop yields, increase soil health as well as improve returns to labour, and thus attract more youth to farming. Overall, the study shows that organic PGS can make vegetable production more economically viable and more agroecologically sustainable.