John Paul II presents Sunday as the weekly celebration of Christ’s Resurrection, the first day of the new creation and the “eighth day” that anticipates eternal life. Rooted in creation, the Sabbath, the Exodus, Pentecost, baptism, and the Apostolic breaking of bread, the Lord’s Day gathers the Church around the twofold table of Scripture and the Eucharist. The Sunday assembly makes ecclesial unity visible, renews faith, and directs the pilgrim Church toward Christ’s return. Catholics are urged to protect Sunday from reduction to a leisure weekend. Participation in Mass is a grave obligation; pastors should provide accessible celebrations, welcome travelers, and preserve the liturgy’s festive character through worthy music, preaching, preparation, and active participation. Prayer assemblies may take place where no priest is available, but cannot replace the Eucharist, while the sick and homebound are encouraged to unite themselves spiritually and receive Communion when possible. Sunday rest should foster family life, contemplation, charity, solidarity with the poor, and works of mercy, with civil society protecting workers’ religious, cultural, and human needs. The annual liturgical year, Marian and saintly commemorations, and the Church’s mission flow from this weekly Easter celebration, entrusted to Mary as the Church journeys toward the eternal Sunday.