Issued for the twentieth anniversary of Populorum Progressio, this social encyclical reads the state of development in the world and finds it worse, not better: a widening gap between North and South, an arms race, and two opposed ideological blocs. Against a purely economic idea of progress it sets authentic integral human development, ordered to the whole person and to every person. It names the 'structures of sin' that flow from the desire for profit and the thirst for power, and answers them with solidarity — not vague compassion but the firm and persevering determination to commit oneself to the common good.