The Liturgy of the Hours is part of the oldest Christian heritage. After being maintained for centuries primarily by clergy and religious orders in the Catholic Church, the goal of the liturgical movement and the Second Vatican Council was to revive the Liturgy of the Hours as a communal celebration and to give it a place in the heart of Christian spirituality. Starting from a historical overview, the book provides insights for the practice of the Liturgy of the Hours. It explores the theological foundations of this prayer culture and includes ecumenical options.