The first Christian theologian to outline a specific scheme for guardian angels was Honorius of Autumn in the 12th century. He said that every soul was assigned a guardian angel the moment it was put into a body. Scholastic theologians augmented and ordered the taxonomy of angelic guardians. Thomas Aquinas agreed with Honorius and believed that it was the lowest order of angels who served as guardians, and his view was most successful in popular thought, but Duns Scotus said that any angel is bound by duty and obedience to the Divine Authority to accept the mission to which that angel is assigned. In the 15th century, the Feast of the Guardian Angels was added to the official calendar of Catholic holidays.
In his March 31, 1997 Regina Caeli address, Pope Saint John Paul II referred to the concept of guardian angel and concluded the address with the statement: "Let us invoke the Queen of angels and saints, that she may grant us, supported by our guardian angels, to be authentic witnesses to the Lord's paschal mystery".
In his 2014 homily for the Feast of Holy Guardian Angels, October 2, Pope Francis told those gathered for daily Mass to be like children who pay attention to their “traveling companion.” “No one journeys alone, and no one should think that they are alone,” the Pope said. During the Morning Meditation in the chapel of Santa Marta, the Pope noted that oftentimes, we have the feeling that “I should do this, this is not right, be careful.” This, he said, “is the voice of” our guardian angel...” “According to Church tradition”, the Pope said, “we all have an angel with us, who guards us...” The Pope instructed each, “Do not rebel, follow his advice!”. The Pope urged that this “doctrine on the angels” not be considered “a little imaginative”. It is rather one of “truth”. It is “what Jesus, what God said: ‘I send an angel before you, to guard you, to accompany you on the way, so you will not make a mistake’”. Pope Francis concluded with a series of questions so that each one can examine his/her own conscience: “How is my relationship with my guardian angel? Do I listen to him? Do I bid him good day in the morning? Do I tell him: ‘guard me while I sleep?’ Do I speak with him? Do I ask his advice? ...Each one of us can do so in order to evaluate “the relationship with this angel that the Lord has sent to guard me and to accompany me on the path, and who always beholds the face of the Father who is in heaven”.
There was an old Irish custom that suggested including in bedtime prayers a request for the Blessed Mother to tell one the name of their guardian angel, and supposedly within a few days one would "know" the name by which they could address their angel. An old Dominican tradition encouraged each novice to give a name to their Guardian Angel so that they could speak to him by name and thus feel closer and more friendly with him. The Congregation for Divine Worship and Discipline of the Sacraments discourages assigning names to angels beyond those revealed in scripture: Michael, Gabriel, and Raphael.