Pius describes the purpose of marriage, insofar as the Catholic church is concerned. He states that marriage does not exist, as some might believe, so that individuals can have sex without fear of repercussion or judgment. It exists for the purpose of producing offspring. He quotes St. Augustine here, who said that:

"The primary end of marriage is the procreation and the education of children."

Marriage can have other benefits, certainly, but its principal function is to produce children and then provide for those children in such a way that they become faithful lovers of God and productive and obedient members of the church.

Pius also addresses the proper role of women in marriage. They must bear and birth the children, and they are also often primarily responsible for the children's education. He quotes St. Augustine again, saying,

"Let women be subject to their husbands as to the Lord, because the husband is the head of the wife, and Christ is the head of the Church."

He specifically says that he does not advocate for an "undignified" state for the wife, but she should enact a companionable obedience to her husband. The relationship between husband and wife should be loving and supportive. However, he also argues that contemporary ideas about the political liberation of women are misguided, as are contemporary ideas about divorce.

Pius expresses his concern, many times, about the progressive politics and ideas that espouse notions of women's freedoms, including sexual independence, divorce, birth control, and abortion. He feels, in many ways, that morality is under attack. He says,

"When we consider the great excellence of chaste wedlock, Venerable Brethren, it appears all the more regrettable that particularly in our day we should witness this divine institution often scorned and on every side degraded."

Pius condemns pop culture texts, such as movies and books, that present marriage as unfulfilling, that show divorce as a completely viable and unproblematic escape from an unhappy marriage, and that show sex as something in which one can and perhaps should participate outside of wedlock. His concern over the state of marriage and morality in general is palpable throughout Casti Connubii.