In the history of Christianity, the term "reform" is commonly used to identify the movement of change in the church started by Martin Luther in the sixteenth century, and the churches that emerged from that movement. However, this concept also designates other realities since the aspiration for reforms in church is present throughout its history. In ecclesiology, the term "reform" indicates the different initiatives for change that focus in doctrine, structures, spiritualities and pastoral projects of the church. It does not indicate ruptures with an ecclesial institution, but its renewal, a tension between continuity and discontinuity in the relationship between essendi modus and operandi modus of the church in every age. In this way, Vatican II should be taken as a council of reform as well as the current moment of the pontificate of Pope Francisco. This paper aims to analyze the possibilities for reform in the Catholic Church, tracing bonds linking between the reformist proposals of the sixteenth century reformers, Vatican II and the current pontificate of Pope Francisco. Thus, the semantic universe of the term "reform" gets here an ecumenical sense, indicating the necessary changes in the different churches in order to promote Christian unity. [ABSTRACT FROM AUTHOR]