This paper builds on the assumption that an effective approach to support the sustainability of natural resource management initiatives is institutional "bricolage." We argue that participatory planning processes can foster institutional bricolage by encouraging stakeholders to make their own arrangements based on the hybridization of old and new institutions. This papers aims at identifying how participatory process facilitators can encourage institutional bricolage. Specifically the paper investigates the specific contextual and procedural drivers of institutional dynamics in two case studies: the Rwenzori region in Uganda and the Fogera woreda in Ethiopia. In both cases, participatory planning processes were implemented. This research has three innovative aspects. First, it establishes a clear distinction between six terms which are useful for identifying, describing, and analyzing institutional dynamics: formal and informal; institutions and organizations; and emergence and change. Secondly, it compares the contrasting institutional dynamics in the two case studies. Thirdly, process-tracing is used to identify contextual and procedural drivers to institutional dynamics. We assume that procedural drivers can be used as "levers" by facilitators to trigger institutional bricolage. We found that facilitators need to pay particular attention to the institutional context in which the participatory planning process takes place, and especially at existing institutional gaps or failures. We identified three clusters of procedural levers: the selection and engagement of participants; the legitimacy, knowledge, and ideas of facilitators; and the design of the process, including the scale at which it is developed, the participatory tools used and the management of the diversity of frames.