Magda B. Arnold (1903-2002), is a pioneering figure of 20th Century emotions research whose pathbreaking and comprehensive theory of emotion is an ambitious fusion of research in cognition, motivation, neuroscience, and personality. Contributors' reviews and critiques of Arnold's work offer a panorama of 20th Century emotion science, revealing where progress has been made, particularly in understanding appraisal processes, and highlighting issues that emotions researchers continue to grapple with, especially questions concerning emotion and value, optimal human functioning, and the complexity of affective and motivational pathways in the brain.Initially drawn to study emotion in the early 1940s because of her interest in personality psychology, Magda Arnold became a leader in the revival of the psychology of emotion, long neglected while behaviourism was the prevailing paradigm. Arnold's life story is no less complex and inspiring than her multifaceted view of human emotion. She was a woman in a field substantially dominated by men, a devout Roman Catholic at a time when the scientific objectivity of Catholic scholars was questioned, and an immigrant, first to Canada and then the U.S., whose early life had provided her with no advantages and little opportunity.Contributors provide insight into the intellectual forebears and theoretical scope of Arnold's emotion theory, and apply her insights to illuminate pressing questions that face contemporary researchers of emotion, motivation, and affective neuroscience.