On November 1, 1950, invoking his dogmatic authority, Pope Pius XII defined the dogma:
"By the authority of our Lord Jesus Christ, of the Blessed Apostles Peter and Paul, and by our own authority, we pronounce, declare, and define it to be a divinely revealed dogma: that the Immaculate Mother of God, the ever Virgin Mary, having completed the course of her earthly life, was assumed body and soul into heavenly glory".
Although the tradition of the Blessed Virgin Mary being assumed in to Heaven has never been a controversy, there is some doubt as to where the Assumption took place.
Two locations claim to be the place of the Assumption of the Blessed Virgin Mary in to Heaven; one in Jerusalem (modern-day Israel) and one in Ephesus (modern day Turkey). Both have fairly strong traditions to support their claims, and both are popular pilgrimage sites.
Regardless of which one it is, we celebrate the Feast of the Assumption of the Blessed Virgin Mary on August 15.
Interestingly, the reported apparitions of the Blessed Virgin Mary in Lubbock, Texas took place on August 15, 1988. This event drew thousands to this West Texas City, although the apparitions themselves have never been approved by the Church. But if you ask many of those present, the reported events were real and not hallucinations!
Note: If the Feast of the Assumption falls on a Saturday (as it does in 2026) it is not considered a Holy Day of Obligation.