Pope Paul VI wrote the encyclical Populorum Progressio in 1967 to address the world economy and its effect on peoples around the world. At this time many nations saw their economic development stall, while others continued to grow at a record pace. In the document he talks about the rights of workers to a just wage, job security, reasonable working conditions, and to join a worker's association.
Catholic Social Teaching
In Laudato Si, a letter addressed to all the people of the world, Pope Francis presents a clear and compelling case for placing people at the center of a renewed commitment to caring for the planet.
“We are faced not with two separate crises, one environmental and the other social, but rather with one complex crisis which is both social and environmental. Strategies for a solution demand an integrated approach to combating poverty, restoring dignity to the excluded, and at the same time protecting nature.” 
Pope Paul VI wrote the Apostolic letter “Octogesima Adveniens” in 1971 as a letter to Cardinal Maurice Roy, the President of the Council of Laity and of the Pontifical Commission on Justice and Peace on the eightieth anniversary of the encyclical Rerum Novarum. His Holiness sought to highlight many social issues facing people at the time and to inspire renewed action for lay members to participate in social and political reform according to the Gospel.
The encyclical Laborem Exercens was written by Pope John Paul II in 1981 to celebrate 90 years since the publication of Rerum Novarum.
In those ninety years issues surrounding employment and labor have not ceased to remain of importance to the Church. Work has changed considerably since the industrial revolution and technological and innovative advances are accelerating that change. In this encyclical His Holiness focuses on the dignity of human work in the contemporary world.
In Sollicitudo Rei Socialis, Pope John Paul II celebrates the twentieth anniversary of Populorum Progressio by updating the Church’s teaching on the “development of peoples” and changes that took place in the preceding two decades.
Populorum Progressio was inspired by the Church’s desire to help the millions of people who lived in a state of poverty and underdevelopment. The document concluded by noting that “development is the new name for peace,” (Paragraph 10) another mission of the Church.
Is the death of a preborn human in the womb really a private matter? Who is not horrified by the evil of genocide? How can a terrorist bombing of a marketplace ever be justified?
"We must begin with a commitment never to intentionally kill," says Living the Gospel of Life "or collude in the killing, of any innocent human life, no matter how broken, unformed, disabled or desperate that life may seem."
The encyclical Centesimus Annus was written in 1991 by Pope John Paul II on the one hundredth anniversary of Rerum Novarum. It came on the heels of the fall of the Berlin Wall and the collapse of the Soviet Union. In it John Paul II seeks to conduct a “re-reading” of Pope Leo’s landmark encyclical to re-discover the richness of the fundamental principles in which Rerum Novarum dealt with the condition of workers and the economy as a whole.
“Every person has a fundamental right to life,” say the U.S. Bishops, “the right that makes all other rights possible. Each person also has a right to the conditions for living a decent life—faith and family life, food and shelter, education and employment, health care and housing. We also have a duty to secure and respect these rights not only for ourselves, but for others, and to fulfill our responsibilities to our families, to each other, and to the larger society.” (Faithful Citizenship: A Catholic Call to Political Responsibility, 2003.)
Pope John Paul II released the encyclical Evangelium Vitae on March 25, 1995. It deals with the most basic of all principles – the value and sacredness of human life. Our duty to protect life is central to the Christian message. The encyclical is broken into four main chapters which discuss contemporary threats to life, the Gospel's message regarding life, God's law, and hope for a new culture of life.