The Lectionary serves as the official liturgical book containing the scripture readings assigned for the celebration of the Mass within the Roman Catholic Church. This volume organizes biblical texts into a structured cycle, ensuring that the faithful encounter the breadth of the Old and New Testaments throughout the liturgical year. It functions as the primary resource for clergy and lectors to facilitate the proclamation of the Word during communal worship.

This text is regarded as the foundational liturgical instrument for Roman Catholic worship, essential for the standardized practice of the Mass. Its authority is derived from its status as an official publication of the Church, ensuring uniformity in the proclamation of scripture across diverse congregations.