Blessed Mother Teresa of Calcutta showed great interest in the apparitions of Garabandal and a long friendship with Conchita. In a letter dated 10 November 1987 to the Bishop of Santander, he tells how he learned about the events in Garabandal.

"It was in 1970, 18 years ago, when he first heard about the apparitions of San Sebastian de Garabandal in Spain." Sometimes it seems like a long time ago and other times it seems like it was yesterday. From the beginning, I felt that the events were true. " 

Mother Teresa met Conchita in person whenever she went to New York. Mother Teresa was also godmother to one of Conchita's sons. She always recommended Conchita total obedience to the Bishop of Santander to speak publicly about Garabandal's apparitions. On one occasion, she asked the Bishop of Santander for permission to conduct an interview on the BBC, Mother Teresa asked the Bishop for the request, but she had previously told Conchita to ask the Bishop for permission and to say that she would do it for Honor and Glory of God and not for any other reason. It was with the help of Mother Teresa's intervention to the Bishop of Santander that the Bishop authorized the filming of Conchita's interview in the 1980s. This interview can be viewed on the youtube website.