A vigil will take place in Tuam this Sunday at the same time as the papal mass in the Phoenix Park to remember those who died in the Tuam Mother and Baby Home.
Historian Catherine Corless, whose work uncovered details of the deaths of 796 babies at the home, also said she declined an invitation from the Taoiseach's office to attend the civil reception with the pope in Dublin Castle this weekend.
Speaking on RTÉ's Morning Ireland, she said it is "just a little statement to say my place is to stand with the survivors."
"The church hasn't helped us; hasn't met survivors," she added.
"We're walking from the Square in Tuam up to the site where we suspect 796 babies are buried."
She also said she had written to the Vatican asking for the pope to meet one of the survivors of the home, but had not heard anything back.
A rally for people affected by clerical abuse is also due to take place at the Garden of Remembrance in Dublin on Sunday at 3pm.
