This article reviews the advancements in the science and practice of psychological well-being, focusing on a model developed over two decades ago to address neglected aspects of positive functioning. The model, known as eudaimonia, emphasizes purposeful engagement in life, realization of personal talents, and enlightened self-knowledge. The article revisits the conceptual origins of this model and examines scientific advancements in six thematic areas: (1) changes in well-being across adult development and later life, (2) personality correlates of well-being, (3) well-being in family life, (4) well-being in work and community activities, (5) connections between well-being and health, and (6) clinical and intervention studies promoting psychological well-being. These topics highlight the broad interest in understanding adults as proactive organisms striving to negotiate life's challenges. Key findings include the health-protective features of psychological well-being, the importance of resilience, and the need for further research and practice. The article also discusses the philosophical and theoretical foundations of the model, the development of assessment tools, and the psychometric properties of the scales used to measure well-being. Finally, it reviews scientific advances in various scientific disciplines, emphasizing the utility of well-being constructs in contemporary research.This article reviews the advancements in the science and practice of psychological well-being, focusing on a model developed over two decades ago to address neglected aspects of positive functioning. The model, known as eudaimonia, emphasizes purposeful engagement in life, realization of personal talents, and enlightened self-knowledge. The article revisits the conceptual origins of this model and examines scientific advancements in six thematic areas: (1) changes in well-being across adult development and later life, (2) personality correlates of well-being, (3) well-being in family life, (4) well-being in work and community activities, (5) connections between well-being and health, and (6) clinical and intervention studies promoting psychological well-being. These topics highlight the broad interest in understanding adults as proactive organisms striving to negotiate life's challenges. Key findings include the health-protective features of psychological well-being, the importance of resilience, and the need for further research and practice. The article also discusses the philosophical and theoretical foundations of the model, the development of assessment tools, and the psychometric properties of the scales used to measure well-being. Finally, it reviews scientific advances in various scientific disciplines, emphasizing the utility of well-being constructs in contemporary research.