Official church figures say the number of Catholics in the world has doubled since 1970.
It's now around 1.2 billion people.
The largest growth came from Africa, where the number of Catholics grew by 238 per cent since 1980.
The number of Catholics in Asia grew by 115 per cent over the same period, while it grew by 56 per cent in the Americas.
While the Catholic Church has struggled with sex abuse and financial scandals, it's thought the growth is partly down to popular papacies like John Paul II and Pope Francis, as well as the church's presence in a high proportion of the world's countries.
By 2050 it's thought 1.6 billion people on the planet will be Catholics.