Participation has become an important issue in landscape planning. Within the relevant literature, an increasing number of authors emphasise the meaning of psycho-social effects such as the building of trust and engagement for planning projects. Yet, empirical studies examining psycho-social effects of participatory techniques in landscape planning are still an exception and are often conceptually and methodologically limited. The present paper addresses these gaps by adapting a mixed method design consisting of repeated measurement (n = 35) and qualitative interviews (n = 11). In the course of a municipal Landscape Development Concept (LDC) in Switzerland, short-term effects were assessed regarding participants' (a) trust in other persons involved, (b) confidence in the outcomes of the LDC, and (c) intention to participate. Significant changes were found on trust in involved persons and on the confidence in the general benefit of the LDC. The intention to participate did not change significantly. Information events had no significant effect on participants, whereas workshops had a significant effect on participants' trust. Trust of workshop attendees decreased during the planning process, which may partly represent a shift from enthusiastic expectations to a more realistic view, and must not be regarded as a negative outcome, since it prevents participants from serious frustration. The paper concludes that a long-term participation strategy, providing different participatory arenas and settings, is essential in order to comprehensively affect all dimensions of trust and to foster engagement. (c) 2007 Elsevier B.V. All rights reserved.