The International Center for Liturgical Studies (CIEL) is an international association of Catholic faithful dedicated to the development of scientific and academic research in the field of liturgical studies. Founded in 1994, CIEL's mission is to promote a methodologically rigorous, historically documented, and theologically structured approach to the Latin liturgical tradition, particularly the usus antiquior of the Roman rite and other Catholic rites.

CIEL is firmly rooted in the fields of historical and theological sciences. It aims to contribute to a better understanding of the sources, structures, and developments of the Roman liturgy by regularly organizing international conferences bringing together researchers, teachers, and specialists from various disciplines: history, dogmatic and sacramental theology, patristics, canon law, philology, and medieval studies. The proceedings of these conferences, most of which have been published, now constitute a scientific reference corpus and are widely available online.

Over more than three decades of activity, CIEL's work has benefited from the participation and support of many prominent figures from the academic and ecclesiastical worlds. These include Cardinal Alfons Maria Stickler, then Prefect of the Vatican Apostolic Library, Cardinal Silvio Oddi, former Prefect of the Congregation for the Clergy, Cardinal Jorge Medina Estévez, Prefect of the Congregation for Divine Worship and the Discipline of the Sacraments, and, more recently, Cardinals Raymond Leo Burke and Robert Sarah. Several diocesan bishops have also taken part in the Center's work, demonstrating institutional interest in liturgical research conducted according to rigorous academic standards.

Through its scientific activity, CIEL is part of an international research dynamic characterized by critical rigor, interdisciplinary dialogue, and a desire to make available to the ecclesial and academic community works based on the analysis of sources and the living tradition of the Church.