The following instruction was released by the Vatican’s Sacred Congregation of the Council on January 12, 1930.
Instruction Concerning the Immodest Dress of Women
(Cfr. Canon 1262, §2)
At the exhortation of His Holiness, Pope Pius XI, to counteract the indecent fashions, many bishops have made regulations in their dioceses and forbidden Catholic ladies to wear fashionable but unbecoming dresses at the sacred functions in church, and especially when receiving Holy Communion. Though they had to suffer the insults that a heathenized press hurled against them, they remained firm in their prohibition of the unchristian fashion. The Sacred Congregation praises them for their constancy and publishes the following regulations:
1. Pastors and preachers shall urge the Catholic women to wear modest dresses, and insist that the mothers stop their daughters from wearing unbecoming apparel.
2. The parents have the obligation to care for the religious and moral education of their children and they must take special care to instruct the girls in the principles of Christian doctrine, and by word and example foster in their souls a love for the virtues of modesty and chastity.
3. The parents must keep the girls away from public gymnastic exercises and exhibitions; if their daughters are forced to take part in such affairs, the parents should see that they wear clothes that are absolutely modest and never allow them to wear immodest uniforms.
4. The heads of girls’ colleges and schools and the teachers must endeavor to instill into the minds of the girls such a love for modesty that they shall detest immodest dress.
5. The heads of schools and the teachers shall not admit to their schools girls who wear unbecoming dress, or whose parents wear them; if those already admitted do not heed the warning, they shall be dismissed from those schools.
6. The religious Sisterhoods shall not admit to their schools, colleges, chapels, or gymnasiums girls who do not dress in a manner becoming Christians, nor shall they tolerate girls already admitted.
7. Pious associations of women should be formed and fostered whose purpose shall be to counteract by example and practical efforts the abuses of the unchristian fashions and to promote purity of morals and decency in dress.
8. Into these associations are not to be received women who do not dress according to Christian modesty, and, if actual members violate the principles of the associations and do not heed the admonition to stop the abuse, they shall be expelled from the associations.
9. Girls and women who wear immodest dress shall be denied Holy Communion, and shall not be admitted as sponsors at Baptism and Confirmation, and, if needs be, shall be stopped from entering any church.
10. On those feast days during the year which present a special opportunity to inculcate Christian modesty, especially the feasts of Our Blessed Lady, the pastors and the priests in charge of women’s societies shall by appropriate sermons exhort the women to wear dresses that bespeak Christian modesty. On the Feast of the Immaculate Conception special prayers shall be offered in all cathedral and parochial churches and, if circumstances permit, an appropriate sermon should be preached.
11. The Diocesan Vigilance Committee, spoken of by the Holy Office on March 22, 1918, should at least once a year meet for the purpose of specially considering ways and means of promoting effectively Christian modesty of women.
12. In order to put these Instructions into effect, the local Ordinaries shall every three years, together with the report on religious teaching (cfr. Motu Proprio, June 29, 1923), inform the Sacred Congregation of the Council on the matter of immodest dress of women and what the Ordinaries have done to counteract that evil.
(Source: Rev. Stanislaus Woywod, Canonical Decisions of the Holy See [New York: J.F. Wagner, 1933], pp. 222-223; Latin original in Acta Apostolicae Sedis XXII , pp. 26-28.)