Publication this year of Pope John XXIII's epochal encyclical Mater et Magistra -- ""Christianity and Social Progress"" --underlines the timelessness of the social message of the Church from the days of Leo XIII to the present. Surprising as it seems, there was again violent controversy about the application of the principles to specific problems. The role of this book may well be that of referee. Magr. Civardi's Christianity And Social Justice deals with the basic principles applicable to family work, poverty and riches, property, charity, authority, liberty, law, love of country and peace. Its near simplicity of expression will surprise those who would expect the technical terminology of the social reformer. Written and translated before publication of the new encyclical, the text is in no way dated. The points made apply perfectly and will serve as a background review of the two major encyclicals which preceded Mater et Magistra, namely Leo XIII's Rerum Novarum, and Pius XI's Quadragesimo Anno (1931). Msgr. Civardi's book offers a plus, too, in reproducing the complete text of the new encyclical. In this day when extremists of both the right and the left are battling about ways of meeting the menace of communism, they would serve the common cause by paying heed to this simple, yet profound, book which expounds the individual's responsibility to restore society to Christ thereby making victory over the common enemy possible.