100 It is Our prerogative to be a Father, and there is a special place in Our thoughts and in Our heart for those professional groups and Christian associations of workers which exist and operate in so many parts of the world. We know the nature and extent of the difficulties under which these dearest sons of Ours are laboring, as they strive continually and effectually to promote in their own countries and throughout the world the material and moral interests of the working people.
Source: Mater et Magistra (Vatican.va)