Letter of the Congregation of the Council on Women and Modesty said:
By virtue of the supreme apostolate which he wields over the Universal Church by Divine Will, our Most Holy Father Pope Pius XI has never ceased to inculcate, both verbally and by his writings, the words of St. Paul (1 Tim. xi,9-10), namely, “Women ... adorning themselves with modesty and sobriety ... and professing godliness with good works.”
Very often, when occasion arose, the same Supreme Pontiff condemned emphatically the immodest fashion of dress adopted by Catholic women and girls -- which fashion not only offends the dignity of women and against her adornment, but conduces to the temporal ruin of the women and girls, and, what is still worse, to their eternal ruin, miserably dragging down others in their fall. It is not surprising, therefore, that all Bishops and other ordinaries, as is the duty of ministers of Christ, should in their own dioceses have unanimously opposed their depraved licentiousness and promiscuity of manners, often bearing with fortitude the derision and mockery leveled against them for this cause.
Therefore this Sacred Council, which watches over the discipline of clergy and people, while cordially commending the action of the Venerable Bishops, most emphatically exhorts them to persevere in their attitude and increase their activities insofar as their strength permits, in order that this unwholesome disease be definitely uprooted from human society. In order to facilitate the desired effect, this Sacred Congregation, by the mandate of the Most Holy Father, has decreed as follows:
Exhortation to Those in Authority
1. The parish priest, and especially the preacher, when occasion arises, should, according to the words of the Apostle Paul (2 Tim. iv, 2), insist, argue exhort and command that feminine garb be based on modesty and womanly ornament be a defense of virtue. Let them likewise admonish parents to cause their daughters to cease wearing indecorous dress.
2. Parents, conscious of their grave obligations toward the education, especially religious and moral, to their offspring, should see to it that their daughters are solidly instructed, from earliest childhood, in Christian doctrine; and they themselves should assiduously inculcate in their souls, by word and example, love for the virtues of modesty and chastity; and since their family should follow the example of the Holy Family, they must rule in such a manner that all its members, reared within the walls of the home, should find reason and incentive to love and preserve modesty.
3. Let parents keep their daughters away from public gymnastic games and contests*; but if their daughters are compelled to attend such exhibitions, let them see that they are fully and modestly dressed. Let them never permit their daughters to don immodest garb.
4. Superioresses and teachers in schools for girls must do their utmost to instill love of modesty in the hearts of maidens confided to their care and urge them to dress modestly.
5. Said Superioresses and teachers must not receive in their colleges and schools immodestly dressed girls, and should not even make an exception in the case of mothers of pupils. If, after being admitted, girls persist in dressing immodestly, such pupils should be dismissed.
6. Nuns, in compliance with the Letter dated August 23, 1928, by the Sacred Congregation of Religious, must not receive in their colleges, schools, oratories or recreation grounds, or, if once admitted, tolerate girls who are not dressed with Christian modesty; said Nuns, in addition, should do their utmost so that love for holy chastity and Christian modesty may become deeply rooted in the hearts of their pupils.
7. It is desirable that pious organizations of women be founded, which by their counsel, example and propaganda should combat the wearing of apparel unsuited to Christian modesty, and should promote purity of customs and modesty of dress.
8. In the pious associations of women those who dress immodestly should not be admitted to membership; but if, perchance, they are received, and after having been admitted, fall again into their error, they should be dismissed forthwith.
9. Maidens and women dressed immodestly are to be debarred from Holy Communion and from acting as sponsors at the Sacraments of Baptism and Confirmation; further, if the offense be extreme, they may even be forbidden to enter the church.
Donato Cardinal Sbaretti, Prefect
Congregation of the Council Rome, January 12, 1930
*While this comment may seem out of place to us today, we must remember the context of the time when it was made, which likely addressed a certain downward trend in dress in sports/gymnastics