Participatory evaluation has been developing over the last several years, particularly in the social sector. Concurrently, research on the effects of evaluation has evolved significantly. Recently, one type of result has been the object of particular attention: the effects and lessons directly attributable to the evaluative process, or process use. Analyses generally underline the direct link between participatory approaches and this type of result. However, few empirical studies testing this concept are available. Our analysis aims to enrich evaluative research on this theme and is founded on a case study of a participatory evaluation project on practices carried out in a social services organization (Centre Jeunesse de Québec - Institut universitaire [Québec Youth Centre - University Institute, Canada]). The results of our analysis show that the evaluative process favours participant learning and has had several direct and indirect effects on the practices of the involved clinical teams. The results also demonstrate the existence of a link between the intensity of actor participation (individuals, groups) and process use. Both constraining factors and factors favourable to participation and the development of the evaluative process are identified, and avenues for improvement are suggested to accentuate the effects of process use.