The media blog at the Web site of the United States Conference of Catholic bishops has a “Social Encyclical Primer” that sets out the history of papal encyclicals on social justice themes.

Christine Gutleben is director of the animals and religion program for the Humane Society of the United States. She has an undergraduate degree in religious studies and a master’s degree from a theology school, where she studied theology and ethical food choices.

Rabbi Harold S. White is Jewish chaplaincy director and senior Jewish chaplain at Georgetown University, where he also teaches in the theology department. He is deeply involved in animal protection issues.

Andrew Linzey is a lecturer in theology at the University of Oxford in Oxford, England . He has written widely on animals and Christianity, including a series of liturgies for animals.

Calvin DeWitt is a professor at the Nelson Institute for Environmental Studies at the University of Wisconsin-Madison. He is concerned with the ethics of farming and uses of the natural environment, including animals. He is co-founder of the International Evangelical Environmental Network.

Eric Reinders is an associate professor of religion at Emory University in Atlanta. He has written about Buddhist attitudes toward animals.

Kerry Walters is a philosophy professor at Gettysburg College in Gettysburg, Pa. With Lisa Portmess, she co-authored two books, one about the history of religious vegetarianism and the other on the history of ethical vegetarianism.

Lisa Portmess is a philosophy professor at Gettysburg College in Gettysburg, Pa. With Kerry Walters, she co-authored two books, one about the history of religious vegetarianism and the other on the history of ethical vegetarianism.

Kimberley Christine Patton is a professor of the comparative and historical study of religion at Harvard University in Cambridge, Mass., where she has taught a course in animals and religion. She is co-editor of A Communion of Subjects: Animals in Religion, Science & Ethics (2006).