...until 1965, fasting and / or complete abstinence were prescribed by the Church for either December 23 or 24.
According to the chapter on "Feasts and Fasts throughout the Year" in The New Marian Missal for Daily Mass, compiled by Fr. Sylvester P. Juergens SM and published by Regina Press, NY, in 1963, December 24 was a day of fasting and complete abstinence in the United Kingdom, Ireland and the USA. In Canada and the Philippines the fasting and abstinence of December 24 were moved to December 23.
Perhaps our readers could indicate in the combox the rules for fasting / abstinence in the two days prior to Christmas that obtained in other parts of the world until 1965.
Since the reform (or rather, the de facto annihilation) of what remained of the traditional Roman regulations for fasting and abstinence beginning in 1966, the fast / abstinence of December 23/24 has been all but forgotten by Catholics; and yet it remains a salutary practice, a fitting way to mark the end of Advent and to prepare our souls for the sweetness of the mysteries of the Christmas season. This short but important penance is especially fitting on December 24, when the traditional Roman liturgy reminds us (amidst what has been called the "holy cheerfulness" of the Church on that day) that Christ is not only our Redeemer, but also our Judge (see the Collect for the Vigil of the Nativity of Our Lord).
(Final revision of this article: Jan. 9, 2011)
(Final revision of this article: Jan. 9, 2011)