[3] Cantwell was raised in Fethard, County Tipperary, where he received his early education at the Monastery National School run by the Patrician Brothers and later the nearby Classical Academy.

[10][11] In addition to four of his brothers, Cantwell's widowed mother and his sister Nellie came to the United States in the 1920s and lived with him at the episcopal residence in Los Angeles.

[12] Upon his arrival in California in late 1899, Cantwell was appointed an assistant pastor to Father Michael O'Riordan, a fellow native of Limerick, at St. Joseph the Worker Church in Berkeley.

[8] On December 5, 1917, four days after his forty-third birthday, Cantwell received his episcopal consecration from Archbishop Hanna, with Bishops Thomas Grace and Joseph Sarsfield Glass serving as co-consecrators, at St. Mary's Cathedral in San Francisco.

[3] In his first public address as Archbishop, Cantwell warned about the threat of communism: "If religion ceases to function, if religious influences are allowed to die, then the work of the Communist, the Bolshevist, and the godless will prosper.

[22][23] In response to this influx, Cantwell declared, "We, in Los Angeles, so close to the Mexican border...cannot be indifferent to the dreadful persecution which is now being waged not only against the Catholic Church but against the most fundamental principles of Christianity.

[23] Cantwell was deeply concerned by the proselytizing efforts of Protestants among Mexican Americans, condemning their work "to tear out of the heart of the foreigner the religion which he has and which alone will save him from becoming an anarchist.

"[25] In recognition of his work among Mexican Americans, Cantwell was given the title of Assistant to the papal throne by Pope Pius XI in September 1929 and was awarded the Golden Rose by the canons of the Basilica of Our Lady of Guadalupe in December 1930.

[26] During his address, he noted that the Ku Klux Klan had persecuted both Blacks and Catholics, and expressed his strong support for the civil rights: The "Imperial Wizard" and the "Grand Goblin" have attempted to read you and me out of our citizenship...You and I know too well what comes from bigotry, from an un-Christian appreciation of human character, to lend ourselves to religious or political prosecution...Indeed, we shall do all in our power when called upon to cooperate and to help you in the vindication of your rights and prerogatives....Religion teaches us to see in every man, no matter what may be the color of his skin, a human soul upon which is stamped the image of God...If men realize the dignity of the human soul apart altogether from external appearances, they will be forced to recognize the equality of all men in the sight of God.

Cantwell opposed government intervention and "any attempt to legislate morality in people,"[31] so Breen persuaded him to propose that his fellow bishops take action against the industry at the annual meeting of the National Catholic Welfare Council (NCWC) in November 1933.

"[32] Cantwell also recruited prominent attorney Joseph Scott to liaise with Hollywood producers and warn that the bishops would launch a campaign against them unless they reformed.

[33] Cantwell told his fellow bishops that films were "preaching a philosophy of life which, in most instances, is...sinister and insidious"[34] and "lowered both the public and private standards of conduct of all who see them.

[33] In June 1934, the Episcopal Committee organized the National Legion of Decency "to arouse millions of Americans to a consciousness of the dangers of salacious and immoral pictures and to take action against them.

"[38] Through the popularity of its rating system and the circulation of membership pledges at church services, the Legion wielded significant influence on the film industry for decades and had millions of members throughout the United States.

"[41] Cantwell celebrated his silver jubilee as a bishop in December 1942, receiving congratulatory messages from Pope Pius XII and President Franklin D.

[3] He received tributes from Mayor Fletcher Bowron, Episcopal bishop Robert Burton Gooden, and actors like Bing Crosby, Bob Hope, Eddie Cantor, and Pat O'Brien.