Resumen: Desde un análisis de documentos magisteriales católico-romanos y ecuménicos, este artículo muestra que la visibilidad histórica de la Iglesia de Cristo, en permanente reforma, se representa de modos diversos. Aunque contiene un alto potencial ecuménico, el reconocimiento de eclesialidad fuera de las fronteras del catolicismo romano, realizada en el Concilio Vaticano II, ha sido defi cientemente recibido en el postconcilio, lo que ha difi cultado desdibujar las fronteras eclesiales y ampliar la comprensión de pertenencia eclesial. Palabras clave: Concilio Vaticano II, fronteras eclesiales, ecumenismo, subsistencia, elementos de Iglesia, pertenencia a la Iglesia Abstract: At analyzing Roman Catholic magisterial documents and, ecumenical ones, we will eventually show that the historical visibility of the Church of Christ –which is to be in continuous reform-, is being recognized as to be represented in various diverse ways. Even if it contains a great ecumenical potential, the conciliar acknowledgment of ecclesiality outside of the Roman Catholic frontiers, has defi ciently been received thereafter. And, as a result of that, fading ecclesial frontiers has become more diffi cult and, a comprehensive understanding of ecclesial belonging too. Keywords: Second Vatican Council, ecclesial frontiers, ecumenism, subsistence, elements of the Church, belonging to the Church