In the Brazilian constitutional experience, the realization of a political transition, from the authoritarian regime installed by the militaries in 1964 to a new democratic order, demanded the convocation of a National Constituent Assembly. All discussions about the procedural rules and the new constitution took shape in the then existing tension between the conservative bloc (majority) and progressive (minority). Despite a huge conservative wing of the resistance, the regimental standards just honoring the popular participation in the process of drafting the constitution, especially through the holding of public hearings and the submission of popular suggestions and amendments to the draft constitution. Direct popular participation mechanisms were also included in the Constitution of the Republic of 1988, aiming to finally break the monopoly of elected representatives with regard to legislative activity and policy decisions, imposing and honoring the exercise of popular sovereignty. This thesis will evaluate the transformation process experienced by the National Constituent Assembly, focusing on the institutional changes and influences that culminated in the adoption, in the bylaws as well as the final text of the Constitution of 1988, direct popular participation mechanisms more focused on the profile of the proposals of the progressive bloc.