Forming social capital—Does participatory planning foster trust in institutions?

•We investigate how trust in institutions is affected by participatory planning.•We focus on the degree of participation and the quality of the participatory process.•The degree has a negative effect while quality improves trust, but not significantly.•Initial trust levels likely affect the perception of participatory planning processes.

Participatory planning that includes interest groups and municipal representatives has been presented as a means to deal with the increasing difficulty to reach arrangements due to progressively scarce land resources. Under dispute is whether collaborative forms of planning augment social capital or whether they might actually cause the destruction of such a valuable social commodity.In this paper we focus on trust in institution as a specific dimension of social capital because we argue that this is one of the effects the convenors of such participatory planning procedures are most interested in. We pursue a pre-post design and survey advisory group members of five on-going river-related planning processes in Switzerland. Controlling for generalised trust, we investigate how trust in institutions is affected over time by the quality of such processes and the degree of participation they offer. We find that generalised trust is highly correlated with initial levels of trust and so is process quality. Particularly the latter finding challenges the usually assumed direction of causality according to which process quality influences trust building. Additionally, we find a positive (non-significant) effect of process quality on changes in trust, while a higher degree of participation rather seems to hinder trust building. We suppose this indicates that under the conditions of limited time and resources more attention should be paid to how to improve the quality of participatory processes than putting much effort in increasing the degree of participation.