Ecclesiam Suam is an encyclical letter of Pope Paul VI on the Catholic Church given at St. Peter's, Rome, on the Feast of the Transfiguration, 6 August 1964, the second year of his Pontificate.

[4] Sean O'Riordan, in The Furrow, noted that the encyclical was issued between the second and third sessions of the Council "to guide the thoughts and aspirations of men, and of his brother bishops in particular, towards the exigencies of the conclusive moment of the Church's history" which was then upon them.

Paul sets out the following aim:To demonstrate with increasing clarity how vital it is for the world, and how greatly desired by the Catholic Church, that the two should meet together, and get to know and love one another.

Paul quotes the encyclical Mystici Corporis of Pope Pius XII, as a key document:Consider, then, this splendid utterance of Our predecessor:"The doctrine of the Mystical Body of Christ, which is the Church, a doctrine revealed originally from the lips of the Redeemer Himself, and making manifest the inestimable boon of our most intimate union with so august a Head, has a surpassing splendor which commends it to the meditation of all who are moved by the divine Spirit, and with the light which it sheds on their minds, is a powerful stimulus to the salutary conduct which it enjoins.

Ecclesiam suam calls the Virgin Mary the ideal of Christian perfection, regarding "devotion to the Mother of God as of paramount importance in living the life of the Gospel".