A burgeoning literature analysing the risks and pitfalls of citizens’ participation highlights the way in which participatory processes often serve to legitimize and support decisions that have already made by public authorities (Cooke and Kothari 2001; Goodin and Dryzek 2006). Constraints placed on citizens are likely to undermine the quality of citizens’ participation, reflecting public managers’ lack of trust in citizens (Aström, 2020). This paper offers a systematic analysis of the "steering mechanisms" applied by public authorities to limit the influence and decision-making power of citizens drawing on a Spanish data set of over 100 Advisory Councils. Advisory Councils are a "traditional" participatory institution (Lowndes et al. 2001) that display the characteristics of associative democracy and collaborative governance in that they engage citizens and representatives of different social groups in dialogue with representatives of the public authority. By exploiting a mixed-method approach, integrating quantitative data on features of the polity (e.g., size, government level), political characteristics (e.g, ideology of governing party) and official documents and rules and qualitative data on participants' perceptions, the paper explores the contextual, political and institutional factors that determine the application of steering mechanisms that constrain the power of citizens.