This book conducts a philosophical analysis of two influential psychological perspectives on emotion research: Arnold’s appraisal theory of emotions and Fredrickson’s broaden-and-build theory of positive emotions. The overarching aim is to illuminate the intrinsic value of (positive) emotions within the framework of human flourishing. In contemporary scholarship, there is a growing acknowledgment that flourishing depends not only on objective, meaningful activities and circumstances, as emphasized by Aristotle, but also on subjective personal life evaluations, where emotional well-being plays a crucial role. This recognition sets the stage for the comprehensive exploration that follows. The study delves into Magda Arnold’s theory, addressing fundamental questions about the nature and unique role of emotions, the meaning of positive emotions, and their relationship to flourishing. Critical elements of Arnold’s theory, including appraisal, self-ideal, referentiality, emotional education, and conative and physiological aspects, are explored. Arnold’s distinctive contribution lies in coining the term “appraisal” and integrating psychological, neurophysiological, and philosophical perspectives on emotion. The analysis of Barbara Fredrickson’s conceptualization of positive emotions as discernible pleasant affective states, such as love, joy, gratitude, and serenity, comprehends her broaden-and-build hypothesis. It underscores the impact of positive emotions on flourishing, focusing on love as a central emotion that broadens thought-action repertoires, fostering perceptions of social connection and self-expansion. This research aims to harmonize the philosophical insights from Arnold’s work with the latest updates from Fredrickson’s research, presenting an avant-garde perspective on how emotion contributes to flourishing. The analysis, rooted primarily in phenomenological insights, extends beyond the boundaries of the authors’ theories. In conclusion, the book offers a nuanced understanding of the intricate relationship between emotion and flourishing, contributing a unique perspective to contemporary discussions in the field. Pía Valenzuela, born in Santiago, Chile, currently serves as a teaching fellow of ethics at the Universidad Panamericana in Mexico. Her teaching experience includes delivering courses on applied ethics at the Faculty of Law and Business Studies, Catholic Institute in Slovenia, and general ethics at the Universidad de los Andes in Santiago, Chile. Prior to her teaching career, she dedicated her time to researching natural law. As a member of the research group “International Law and Religion,” she actively contributed to the project “Intellectual History of International Law: Religion and Empire” (2013-2017) at The Erik Castren Institute, University of Helsinki, Finland. While maintaining a persistent interest in ethics, her focus shifted to moral, positive, and philosophical psychology. She developed a keen interest in the interdisciplinary dialogue between philosophy and psychology, particularly in their perspectives on emotion. Currently, her research revolves around the intricate relationship between emotion, virtue, and flourishing, specifically emphasizing positive emotions. Pía Valenzuela participates in several professional organizations, including the European Philosophical Society for the Study of Emotions (EPSSE), Società Italiana di Psicologia Positiva (SIPP), and the Network for Research on Morality (NRM), among others. She actively contributes to the research group Human Flourishing at the Pontifical University of the Holy Cross in Rome and is associated with Magda Arnold’s Scholars.