American philosopher Josiah Royce (1856-1916) delivered three lectures on the topic of loyalty at the Twentieth Century Club in Pittsburgh in February 1909. These lectures, “The Conflict of Loyalties,” “The Art of Loyalty,” and “Loyalty and Individuality,” are indispensable for a complete and coherent picture of the development of Royce’s philosophy of loyalty. This publication marks the first appearance of these lectures in a book, making them widely accessible to readers. Included in this volume is an Editor’s Introduction by Mathew A. Foust, a preeminent scholar of Royce’s philosophy of loyalty. Foust details the mysteries long surrounding these lectures and the clues that led to their solutions. Foust then demonstrates how the 1909 Pittsburgh Loyalty Lectures constitute a “missing link” between The Philosophy of Loyalty (1908) and subsequent works by Royce such as “Loyalty and Insight” in William James and Other Essays on the Philosophy of Life (1911), The Sources of Religious Insight (1912), The Problem of Christianity (1913), War and Insurance (1914), and The Hope of the Great Community (1916). Students and scholars of American Studies, the history of philosophy, ethics and moral philosophy, and social philosophy will find much of enduring relevance in Josiah Royce’s 1909 Pittsburgh Loyalty Lectures.