The life and work of John Lancaster Spalding focused on the importance of Catholic ideals of life and education in the development of the human person and society in order to fit them to the high purpose of participating in God's reign on earth and preparation for humanity's ultimate end--eternal life with God. Following a brief biographical introduction, this article addresses the central themes of Bishop Spalding's social thought and proposes that his attempts to articulate a Catholic perspective on social justice issues of his time were among the earliest in the United States. The article concludes by focusing on the importance of the role of education in Spalding's social thought and proposes some implications for the teaching of peace and justice today.