Our Lady of the Assumption
The title “Our Lady of the Assumption” is one of the newest titles ascribed to Our Blessed Mother insofar as the doctrine of the Assumption was not dogmatically defined until November 1, 1950 when Pope Pius XII invoked papal infallibility in his writing entitled “Munificentissimus Deus”.
The Assumption of Mary, of course, is the Roman Catholic and Eastern Orthodox belief that the Virgin Mary was bodily taken up into heaven at “the end of her earthly life”. While this doctrine was not formally defined until the middle of the 20th century, the belief that Mary has taken her rightful place in heaven – although whether or not she experienced physical death before her Assumption into glory has been the subject of widespread debate and discussion – has circulated in various apocryphal Church writings dating back to the 4th century. St. Gregory of Tours was the first Christian author to speak of the bodily Assumption of Mary, and Popes Sergius I and Leo IV celebrated this feast of Mary centuries before Pope Pius XII’s 1950 dogmatic proclamation.
Various scriptural citations ranging from Genesis 3:15  to Psalm 132 to 1 Corinthians 15  to Revelation 12:1-2 have been interpreted  as justification of this Church doctrine. The Church celebrates this feast on August 15th, which many countries designate as a holyday of obligation, while the Eastern Orthodox Church celebrates Mary’s Assumption, which it refers to as the “Dormition of the Theotokos”, on August 28th.