Pope John XXIII’s prayerful phrase “a new Pentecost” linked Vatican II with the Holy Spirit and has interpretative potential. It focuses the pneumatological dimensions of the epochal event and documents. The article considers Pentecost in the constitution of the church, emphasizes the pneumatological difference, underlines the finality of Vatican II toward renewal in the church’s (now dialogical) mission, and concludes to a completeness in the council.