The field of scientific research on synods and synodality, regarding Belgian Protestantism of the Reformed type, with the presbytero-synodal regime, is untouched. This is a first-time study, original, clearing a small portion of it, for ecclesiological purposes. This portion covers the period extending from 1979, which is the effective start of the United Protestant Church of Belgium (EPUB), to 2005, the year of the beginning of the implementation of the new shape of Belgian Protestantism recognized by the public authorities in 2003, the Administrative Council of the Protestant and Evangelical Worship (CACPE). In use in this thesis is the correlative method, an empirical method that puts into dialogue a trilogy known as that of three "E’s" (in French language), which Laurent Gagnebin calls "triangular correlation", i.e.: (1) "Holy Scriptures (Écritures Saintes)"; (2) "Ecclesial Teachings (Enseignements ecclésiastiques)" (or tradition) (here, comprising the synodal documents) and (3) "Experiences" (here, interviews). A questioning presides over this approach: What Church way of life could the study of synods and synodality in the EPUB allow for further study? In its ecclesiology (to be discovered), what is the way of connecting ordained ministers and lay people in decision-making? How is the "one-to-one" for all articulated? What are the keys to synod assemblies’ delegation? What is the dimension of Christ's representation in the minds of the delegates: do they feel like they represent Christ, their local Churches, their districts or what else? How are, and according to what mode, the consistory (local level), the district council (regional level), the Synod Council (national level) coordinated in the decision-making in relation to synodal activity? Is it a democratic or synodal process? To the extent that the Church is itself received from Christ, is it really democratic? From this perspective, what about the "vote" aspect? Where is the foundation in Christ, the common ministry, performed? Is the Church an ...